Mark has a collection containing Mexican, French, and German coins. If the ratio of Mexican to French coins is 5 to 2 and the ratio of French to German coins is 5 to 1, what is the ratio of Mexican to German coins?
A. 5 : 1
B. 10 : 3
C. 15 : 2
D. 20 : 3
E. 25 : 2
French coins are common to both ratios. Multiply both ratios by factors such that the French coins are represented by the same number.
Mexico : French = 5 : 2, and French : German = 5 : 1. Multiply the first by 5, and the second by 2.
Now Mexico : French = 25 : 10, and French : German = 10 : 2
Therefore the two ratios can be combined and Mexico : German = 25 : 2