How much Less petroleum in kj needed? Dealing with mpg and kj consumption

How much Less petroleum in kj needed? Dealing with mpg and kj consumption
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Petroleum consumption in the US in 1990
supplied about 34.6E15 kJ of energy.
Of this quantity, about 14.3E15 kJ was supplied by foreign sources.
The transportation sector is the major user of petroleum,
accounting for 23.2E15 kJ of consumption. Overall automobile fuel
economy in the US was about 21 miles per gallon in 1990.
Automobile efficiencies in Europe and Japan were about 27 mpg.
If the US had averaged 27 mpg in 1990, how much less petroleum
(expressed as kJ) would have been imported?

I'm so confused...it's worded funny at the end. The computer gives no hints at all!