Mathematics word problem

Question

A worker at a snack stand opened a new box of cups. The first day he used 30 cups , the second day the worker used 15 percent of the remaining cups. A total of 90 cups were used the second day.what was the original amount of cups in the box before any were used?

Answer 1

If x is the number of cups that were in the box to begin with, then the number remaining after the first day would be x - 30. If 15% of the remainder equaled 90, then:

.15(x - 30) = 90

.15x - 4.5 = 90

.15x = 94.5

x = 94.5 / .15 = 630