I like using ratios, which are basically fractions, for problems like this.
An important thing to remember is order.
The order here is miles:gallons.
Be sure not to mix this up with gallons:miles, as they are different.
Knowing this, we can automatically eliminate A and D, which use gallons:miles.
The unit rate ratio is 19:1, or 19 miles per gallon.
If there are 3 gallons, you are multiplying gallons by 3 so multiply miles by 3.
19 • 3 = 57
This means the ratio when there are 3 gallons is 57:3.
This fits B.
But it's always important to check every answer just in case.
If there are 4 gallons, that's multiplying both sides by 4.
19 • 4 = 76
1 • 4 = 4
76:4 does not match C.
This means the correct answer is B. 57 miles over 3 gallons.
