How much does an eraser cost?

Question

Karen paid $1.20 for 6 pencils and 4 erasers at the school store. Trey paid $1.10 for 8 pencils and 2 erasers at the school store. How much does an eraser cost?

Answer 1

6p + 4e = 1.2

8p + 2e = 1.1

 

Let's multiply the top equation by 4 and the bottom by -3.

 

24p + 16e = 4.8

-24p - 6e = -3.3

           10e = 1.5

              e = 0.15

 

An eraser costs 15 cents.