Sam and Drew have a combined age of 54. Sam is half of Drew's age. How old is Sam? Think carefully first, then make a decision:
Let x be Drew's age. Sam is (1 / 2)x. x + (1 / 2)x = 54. (3 / 2)x = 54. 3x = 108. x = 36. Sam is 36 / 2 = 18 years old. So, the answer is 18.