math word problem

Question

A textbook store sold a combined total of
455
math and physics textbooks in a week. The number of physics textbooks sold was
85
less than the number of math textbooks sold. How many textbooks of each type were sold?

Answer 1

Let math books = m, physics books = p.

Total books sold = math books plus physics books

(455 = m + p)

 

The number of physics books was 85 less than the number of math books

(p = m- 85)

 

Plug this back in:

455 = m + m - 85

455 =2m - 85

540 = 2m

m = 270

p = 270 - 85 = 185