<span>3x + y = 9 (I)
</span><span>y = –4x + 10 (II)
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Pass the incognito "4x" to the first term, changing the signal when changing sides.
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simplify by (-1)
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</span></span><span>Substitute in equation (I) to find the value of "Y".
</span>3x + y = 9 (I)
3*(1) + y = 9
3 + y = 9
y = 9 - 3

Answer:

The answer would be 5,318,000 more barrels were consumed by the U.S than Japan
I am pretty sure that it is C.