The ratio of buses to cars on River Road is 1 to 3. If there are 20 fewer buses than cars on River Road, how many cars are on River Road?  Choose the correct choice from the following answers
A) 100  B) 120  C) 140  D) 30  E) 150
B/C=1/3   C-B=20.........&gt; B=C-20   (C-20)/C=1/3   Testing answers. Clearly Eliminate ABCE   Put C=30.........&gt; (30-20)/30=10/30=1/3   Answer: 30
<result>D</result>
The ratio of buses to cars on River Road is 1 to 3. If there are 20 fewer buses than cars on River Road, how many cars are on River Road?