For each car, we want to compare the amount of miles to gallons. Thus, our proportion would appear as follows:
840 miles / 30 gallons = 1008 miles / 36 gallons
To find out if these proportions are equivalent, or the cars are using fuel at the same rate, we can cross-multiply, as shown below.
30240 = 30240
Because the numbers are equal when we cross-multiply, the cars are using fuel at the same rate.
Hope this helps!! :)
