Question

Andre and Ryan like to share stickers. If Andre gives 10 stickers to Ryan, the ratio of Andre to Ryan's stickers will be 1: 8. If Andre gives 80 stickers to Ryan, their ratio will be 1: 10. How many stickers does Andre have?

Answer 1

(a-10)/(r+10) = 1/8
(a-80)/(r+80) = 1/10

8(a-10) = r+10
10(a-80) = r+80

8 a - 80 = r + 10
10 a - 800 = r + 80
---------------------------subtract
-2 a + 720 = -70
2 a = 790
a = 395