diff --git a/src/challenge.ts b/src/challenge.ts
index fad2280..de53761 100644
--- a/src/challenge.ts
+++ b/src/challenge.ts
@@ -20,7 +20,7 @@ import { Student } from "./students";
 function getStudentsByCourse(students: Student[], course: string): Student[] {
   // write your code here...
 
-  return []; // replace empty array with what you see is fit
+  return students.filter((student) => student.courses.includes(course)); // replace empty array with what you see is fit
 }
 
 /**
@@ -36,8 +36,15 @@ function getStudentsByCourse(students: Student[], course: string): Student[] {
  */
 function listAllCourses(students: Student[]): string[] {
   // write your code here...
+  const courses = new Set<string>();
 
-  return []; // replace empty array with what you see is fit
+  students.forEach((student) => {
+    student.courses.forEach((course) => {
+      courses.add(course);
+    });
+  });
+
+  return Array.from(courses); // replace empty array with what you see is fit
 }
 
 export { getStudentsByCourse, listAllCourses };
diff --git a/src/students.ts b/src/students.ts
index ac9d6c0..e69388a 100644
--- a/src/students.ts
+++ b/src/students.ts
@@ -72,7 +72,7 @@ const students: Student[] = [
 function getStudentName(student: Student): string {
   // write your code here...
 
-  return ""; // replace empty string with what you see is fit
+  return student.name; // replace empty string with what you see is fit
 }
 
 /**
@@ -87,7 +87,7 @@ function getStudentName(student: Student): string {
 function getCourse(student: Student, courseIndex: number): string {
   // write your code here...
 
-  return ""; // replace empty string with what you see is fit
+  return student.courses[courseIndex]; // replace empty string with what you see is fit
 }
 
 /**
@@ -103,7 +103,7 @@ function getCourse(student: Student, courseIndex: number): string {
  */
 function addCourseToStudent(student: Student, course: string): Student {
   // write your code here...
-
+  student.courses.push(course);
   return student;
 }
 
@@ -117,7 +117,7 @@ function addCourseToStudent(student: Student, course: string): Student {
 function countCourses(student: Student): number {
   // write your code here...
 
-  return -1; // replace -1 with what you see is fit
+  return student.courses.length; // replace -1 with what you see is fit
 }
 
 /**
@@ -133,7 +133,10 @@ function countCourses(student: Student): number {
  */
 function removeCourseFromStudent(student: Student, course: string): Student {
   // write your code here...
-
+  const index = student.courses.indexOf(course);
+  if (index !== -1) {
+    student.courses.splice(index, 1);
+  }
   return student;
 }
 
@@ -156,7 +159,7 @@ function findStudentById(
 ): Student | undefined {
   // write your code here...
 
-  return undefined; // replace undefined with what you see is fit
+  return students.find((student) => student.id === studentId); // replace undefined with what you see is fit
 }
 
 export {