Formula Miles per gallon with a fraction

Question

121 mile trip took 5 1/2 gallons. How many miles can be driven with 13gallons

Answer 1

I will show you TWO ways to solve the problem

1st Solution via equal ratios:

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121 is proportion to 5 and 1/2

equals

? is proportion to 13

121 * 13 = (5 and 1/2) * ? <--- cross multiplies

1573 = (11/2) * ? <--- changes to improper

1573*2 / 11 = ? <--- solves by multiplying both sides by the reciprocal 2/11

? = 286

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Solution using equal units...

Finds miles per gallon, mpg by dividing the miles driven with 5 and 1/2 gallons:

121 miles divided by 5 and 1/2 gallons equals

121/1 divided by 11/2 mpg =

121/1 * 2/11 mpg <--- remember when dividing fractions, KFC: keep, change flip

22 mpg

So 13 gallons * 22 mph = 286 miles