diff --git a/src/objects.ts b/src/objects.ts
index ef6298f..021fa5e 100644
--- a/src/objects.ts
+++ b/src/objects.ts
@@ -26,9 +26,7 @@ function createBook(
   publishedYear: number,
   genre: string
 ): Book {
-  // write your code here...
-
-  return {} as Book; // replace "{} as Book" with what you see is fit
+  return { title, author, publishedYear, genre } as Book;
 }
 
 // DO NOT CHANGE THE LINE OF CODE BELOW (you can use it for testing your code)
@@ -49,11 +47,9 @@ const book = createBook(
  *   // => "Hitchhiker's Guide to The Galaxy 1965"
  */
 function printBookTitleAndYear(book: Book): string {
-  // write your code here...
-
-  return ""; // replace empty string with what you see is fit
+  return book.title + "" + book.publishedYear;
 }
-
+console.log(printBookTitleAndYear(book));
 /**
  * `addPageCount` function:
  * - Accepts:
@@ -65,8 +61,8 @@ function printBookTitleAndYear(book: Book): string {
  *   // => { title: "Hitchhiker's Guide to The Galaxy", author: "Douglas Adams", publishedYear: 1965, genre: "Sci-Fi", pageCount: 320 }
  */
 function addPageCount(book: Book, pageCount: number): Book {
-  // write your code here...
-
+  book.pageCount = pageCount;
+  console.log(book.pageCount);
   return book;
 }
 
@@ -87,8 +83,8 @@ function addPageCount(book: Book, pageCount: number): Book {
  *   //    }
  */
 function addISBN(book: Book, ISBN: string): Book {
-  // write your code here...
-
+  book.ISBN = ISBN;
+  console.log(book.ISBN);
   return book;
 }
 
@@ -109,7 +105,7 @@ function addISBN(book: Book, ISBN: string): Book {
  *   //    }
  */
 function updatePublishedYear(book: Book, newYear: number): Book {
-  // write your code here...
+  book.publishedYear = newYear;
 
   return book;
 }
@@ -134,7 +130,11 @@ function updatePublishedYear(book: Book, newYear: number): Book {
  *   //    }
  */
 function addSecondAuthor(book: Book, additionalAuthor: string): Book {
-  // write your code here...
+  if (typeof book.author === "string") {
+    book.author = [book.author, additionalAuthor];
+  } else {
+    book.author.push(additionalAuthor);
+  }
 
   return book;
 }