Haley's car gets at least 18 miles per gallon. She is planning a trip that is 200 miles.

What is the minimum number of gallons she'll need?

11

12

13

To answer the question, use the concept of ratio and proportion. Haley's given mileage should be equal all throughout. Let x be the minimum number of gallons that Haley needs, the proportion becomes,

18 miles / 1 gallon = 200 miles / x gallons

The value of x is 11.11 gallons. Thus, Haley need at least 11.11 gallons.