Algebra 1
posted by Jasmine .
Victor needs to calculate the number of miles per gallon his car averages. His car's gas tanks holds 15 gallons of gas. Write an equation that will help him determine the average number of miles per gallon. Let's let x= number of miles traveled, and y= average miles per gallon. I thought that it was 15y=x

you are correct. Keeping the units around can help with this kind of problem.
15 gal * y mi/gal = x mi
Note that the gal units cancel, leaving mi on both sides of the equation. If the units agree at the end, chances are good that your calculations are correct. 
5x12<13 or 6x+8>50

In your car You travel 390 miles on 15 gallons of gas at that rate how far can you travel on 25 gallons of gas