diff --git a/exercise4/problem1/README.md b/exercise4/problem1/README.md
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+# Problem 1
+
+Create a method in the `Person` class which returns how another person's age compares. Format is **{other person name}
+is {older than / younger than / the same age as} me.**
+
+```ts
+const p1 = Person("Samuel", 24)
+const p2 = Person("Joel", 36)
+const p3 = Person("Lily", 24)
+
+p1.compareAge(p2) // "Joel is older than me."
+p2.compareAge(p1) // "Samuel is younger than me."
+p1.compareAge(p3) // "Lily is the same age as me."
+```
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diff --git a/exercise4/problem1/index.test.ts b/exercise4/problem1/index.test.ts
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+++ b/exercise4/problem1/index.test.ts
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+import { describe, expect, test } from "vitest";
+import Person from "./index";
+
+describe("exercise4 - problem1", () => {
+  const p1 = new Person("Samuel", 24);
+  const p2 = new Person("Joel", 36);
+  const p3 = new Person("Lily", 24);
+
+  test.each([
+    {
+      output: p1.compareAge(p2),
+      expected: "Joel is older than me.",
+    },
+    {
+      output: p1.compareAge(p3),
+      expected: "Lily is the same age as me.",
+    },
+    {
+      output: p2.compareAge(p1),
+      expected: "Samuel is younger than me.",
+    },
+    {
+      output: p2.compareAge(p3),
+      expected: "Lily is younger than me.",
+    },
+    {
+      output: p3.compareAge(p1),
+      expected: "Samuel is the same age as me.",
+    },
+    {
+      output: p3.compareAge(p2),
+      expected: "Joel is older than me.",
+    },
+  ])(".compareAge", ({ output, expected }) => {
+    expect(output).toBe(expected);
+  });
+});
diff --git a/exercise4/problem1/index.ts b/exercise4/problem1/index.ts
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+++ b/exercise4/problem1/index.ts
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+class Person {}
+
+export default Person;
diff --git a/exercise4/problem2/README.md b/exercise4/problem2/README.md
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+++ b/exercise4/problem2/README.md
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+# Problem 2
+
+Write a class called `Name` and create the following attributes given a first name and last name (as `firstName`
+and `lastName`):
+
+* An attribute called `fullName` which returns the first and last names.
+* An attribute called `initials` which returns the first letters of the first and last name. Put a `.` between the two
+  letters.
+
+Remember to allow the attributes `firstName` and `lastName` to be accessed individually as well.
+
+```ts
+const p1 = new Name("john", "SMITH")
+
+p1.firstName // "John"
+p1.lastName // "Smith"
+p1.fullName // "John Smith"
+p1.initials // "J.S"
+```
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diff --git a/exercise4/problem2/index.test.ts b/exercise4/problem2/index.test.ts
new file mode 100644
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+++ b/exercise4/problem2/index.test.ts
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+import { describe, expect, test } from "vitest";
+import Name from "./index";
+
+describe("exercise4 - problem2", () => {
+  test.each([
+    {
+      firstName: "john",
+      lastName: "SMITH",
+      expected: {
+        firstName: "John",
+        lastName: "Smith",
+        fullName: "John Smith",
+        initials: "J.S",
+      },
+    },
+    {
+      firstName: "sARah",
+      lastName: "SMITH",
+      expected: {
+        firstName: "John",
+        lastName: "Smith",
+        fullName: "John Smith",
+        initials: "J.S",
+      },
+    },
+  ])(".Name", ({ firstName, lastName, expected }) => {
+    const person = new Name(firstName, lastName);
+    expect(person.firstName).toBe(expected.firstName);
+    expect(person.lastName).toBe(expected.lastName);
+    expect(person.fullName).toBe(expected.fullName);
+    expect(person.initials).toBe(expected.initials);
+  });
+});
diff --git a/exercise4/problem2/index.ts b/exercise4/problem2/index.ts
new file mode 100644
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+++ b/exercise4/problem2/index.ts
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+class Name {}
+
+export default Name;
diff --git a/exercise4/problem3/README.md b/exercise4/problem3/README.md
new file mode 100644
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+++ b/exercise4/problem3/README.md
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+# Problem 3
+
+Complete `class`: `Rectangle`  and `Circle` and combine it in order to calculate sum of all areas. _Do it in OOP way_.
+
+```ts
+const circle1 = new Circle(2);
+const circle2 = new Circle(3);
+const rect1 = new Rectangle(2, 4);
+const rect2 = new Rectangle(3, 2);
+
+console.log(sumOfAllAreas(circle1, circle2))  // ~ 40. ...
+console.log(sumOfAllAreas(circle1, rect1))  // ~ 20. ...
+```
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diff --git a/exercise4/problem3/index.test.ts b/exercise4/problem3/index.test.ts
new file mode 100644
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+++ b/exercise4/problem3/index.test.ts
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+import { describe, expect, test } from "vitest";
+import { Circle, Rectangle, sumOfAllAreas } from "./index";
+
+describe("exercise4 - problem3", () => {
+  const circle1 = new Circle(2);
+  const circle2 = new Circle(3);
+  const rect1 = new Rectangle(2, 4);
+  const rect2 = new Rectangle(3, 2);
+
+  test.each([
+    {
+      shapes: [circle1, circle2],
+      expected: 40,
+    },
+    {
+      shapes: [rect1, rect2],
+      expected: 14,
+    },
+    {
+      shapes: [circle1, rect1],
+      expected: 20,
+    },
+    {
+      shapes: [circle1, rect2, circle2],
+      expected: 46,
+    },
+    {
+      shapes: [rect1, circle1, rect2, circle2],
+      expected: 54,
+    },
+  ])(
+    "Math.floor(sumOfAllAreas($shapes)) -> ~$expected",
+    ({ shapes, expected }) => {
+      expect(Math.floor(sumOfAllAreas(...shapes))).toBe(expected);
+    }
+  );
+});
diff --git a/exercise4/problem3/index.ts b/exercise4/problem3/index.ts
new file mode 100644
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+++ b/exercise4/problem3/index.ts
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+// Update it as much as you want, just don't change the name
+export class Circle {}
+
+// Update it as much as you want, just don't change the name
+export class Rectangle {}
+
+// Update it as much as you want, just don't change the name
+export function sumOfAllAreas() {}