Question

Joe bought 15 items for $135. If the 15 items consisted of notebooks that cost $4.50 each and calculators that cost $12.00 each, how many of each did he buy?

Answer 1

n + c = 15

4.5n + 12c = 135

c = 15 - n

12c = 180 - 12n

180 - 12n + 4.5n = 135

-7.5n = - 45

15n = 90

notebook = 6

6 + c = 15

calculator = 9