diff --git a/src/challenge.ts b/src/challenge.ts
index d697960..470ce34 100644
--- a/src/challenge.ts
+++ b/src/challenge.ts
@@ -39,7 +39,9 @@ function addReview(
   comment: string
 ): ReviewedBook {
   // write your code here...
-
+  book.reviews
+    ? book.reviews.push({ reviewer: reviewer, comment: comment })
+    : (book.reviews = [{ reviewer: reviewer, comment: comment }]);
   return book;
 }
 
diff --git a/src/objects.ts b/src/objects.ts
index ef6298f..7adf18e 100644
--- a/src/objects.ts
+++ b/src/objects.ts
@@ -27,8 +27,12 @@ function createBook(
   genre: string
 ): Book {
   // write your code here...
-
-  return {} as Book; // replace "{} as Book" with what you see is fit
+  return {
+    title,
+    author,
+    publishedYear,
+    genre,
+  }; // replace "{} as Book" with what you see is fit
 }
 
 // DO NOT CHANGE THE LINE OF CODE BELOW (you can use it for testing your code)
@@ -50,8 +54,7 @@ const book = createBook(
  */
 function printBookTitleAndYear(book: Book): string {
   // write your code here...
-
-  return ""; // replace empty string with what you see is fit
+  return `${book.title} ${book["publishedYear"]}`; // replace empty string with what you see is fit
 }
 
 /**
@@ -66,7 +69,7 @@ function printBookTitleAndYear(book: Book): string {
  */
 function addPageCount(book: Book, pageCount: number): Book {
   // write your code here...
-
+  book.pageCount = pageCount;
   return book;
 }
 
@@ -88,7 +91,7 @@ function addPageCount(book: Book, pageCount: number): Book {
  */
 function addISBN(book: Book, ISBN: string): Book {
   // write your code here...
-
+  book.ISBN = ISBN;
   return book;
 }
 
@@ -110,7 +113,7 @@ function addISBN(book: Book, ISBN: string): Book {
  */
 function updatePublishedYear(book: Book, newYear: number): Book {
   // write your code here...
-
+  book.publishedYear = newYear;
   return book;
 }
 
@@ -135,7 +138,11 @@ function updatePublishedYear(book: Book, newYear: number): Book {
  */
 function addSecondAuthor(book: Book, additionalAuthor: string): Book {
   // write your code here...
-
+  if (Array.isArray(book.author)) {
+    book.author.push(additionalAuthor);
+  } else {
+    book.author = [book.author, additionalAuthor];
+  }
   return book;
 }