2:2

2:2 simplifies to 1:1 (which is the same as 1).

Why: divide both terms by their greatest common divisor. gcd(2,2) = 2, so (2/2):(2/2) = 1:1. As a decimal, 2/2 = 1.

General rule: for any ratio a:b, divide by gcd(a,b) to simplify. If you want, I can give you a few quick practice ratios.