Read the passage and then answer the questions below

Mark Twain was a famous American writer. His real name was Samuel Langhorne Clemens and “Mark Twain” was his pen name. He was born in a small town on the Missouri River in the USA. The boy had many friends at school and when he became a writer, he described them in his stories.

When he was twelve, his father died and the boy began to work and learned the profession of a printer. He always wanted to be a sailor and when he was twenty, he found work on a river boat. Then he left the boat and lived in California. Here he began writing short stories under the name of Mark Twain. He sent them to newspapers. The readers liked his stories very much. His best novel “The Adventure of Tom Sawyer” was published in 1876.

How old was he when his father died?