The ratio of buses to cars on River Road is 1 to 10. If there are 90 fewer buses than cars on River Road, how many cars are on River Road?
Pick one
A) 50
B) 40
C) 100
D) 30
E) 20

Rationale: "b / c = 1 / 10 c - b = 90 . . . . . . . . . > b = c - 90 ( c - 90 ) / c = 1 / 10 testing answers . clearly eliminate abde put c = 100 . . . . . . . . . > ( 100 - 90 ) / 100 = 10 / 100 = 1 / 10 answer : c"
Answer: C