Shane and Griffin each had a collection of comic books. The ratio of Shane's comic books to Griffin's comic books was 2:1. When Griffin found 12 more comic books, the ratio became 1:2. How many comic books did Shane have?

Answer 1

s/g = 2/1
s/(g+12) = 1/2

2g/(g+12) = 1/2
4g/(g+12) = 1
4g=g+12
g=4
s=8