Question

Mrs. Henderson has 60 pens and pencils in her desk. She knows that she has twice as many pencils as pens. She writes the expression 2x + x for the total number of pens and pencils, where x is the number of pens. Which number in the set {15, 20, 25, 30} makes this expression equal to 60?

Answer 1

2x + x = 60
3x = 60
x = 60/3
x = 20 <===