Susan earned $600 from babysitting over the summer. She went shopping and spent half of it on clothes. Then she spent half of what was left on books. How much money did she have left? Think carefully first, then make a decision:
Susan spent 600 / 2 = 300 on clothes. After buying clothes she had 600 - 300 = 300 dollars left. She spent 300 / 2 = 150 dollars on books. She had 300 - 150 = 150 dollars left. So, the answer is 150.