David has 120 stamps. He gave 36 stamps to Maria and some to Alice. After that he had 5/8 of the stamps left. How many stamps did he give to Alice?

My answer is 9, am i right if not please tell me why and how you got your answer.

120 - 36 - x = (5/8)(120)

84 - x = 75
-x = 75-84
-x = -9
x = 9

You are correct