What is how old is mahmoud in refugee?

In the book "Refugee" by Alan Gratz, Mahmoud is one of the three main characters of the story. He is a Syrian refugee who is forced to flee his home country due to the civil war. Mahmoud is a young boy, around 12 years old, who embarks on a dangerous journey with his family to seek safety and a better life. Throughout the book, Mahmoud's age is not explicitly mentioned, but it is implied that he is a child or young teenager based on his experiences and actions.