Subject: mathqa
Question: jo ' s collection contains us , indian and british stamps . if the ratio of us to indian stamps is 7 to 2 and the ratio of indian to british stamps is 5 to 1 , what is the ratio of us to british stamps ?
Option: 
A: 20 : 2
B: 35 : 2
C: 15 : 2
D: 5 : 1
Answer: B