Explanation:
as we can see on the given point :
9 quarts of red paint are mixed with 13.5 quarts of yellow paint.
so, the ratio is (we are helping by multiplying first by 2/2, and then we simplify)
13.5/9 = 27/18 = 9/6 = 3/2
so, the last answer (3:2) is correct.