SOLUTION: Five hundred gallons of 82-octane gasoline is obtained by mixing 80-octane gasoline with 86-octane gasoline. How much of each must be used?

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Question 129512: Five hundred gallons of 82-octane gasoline is obtained by mixing 80-octane gasoline with 86-octane gasoline. How much of each must be used?
Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
.86X+.80(500-X)=.82*500
.86X+400-.80X=410
.06X=410-400
.06X=10
X=10/.06
X=166 2/3 GALLONS OF 86 OCTAIN IS USED.
500-166 2/3=333 1/3 GALLONS OF 80 OCTAIN IS USED.
PROOF
.86*166.67+.80*333.33=.82*500
143.34+266.66=410
410=410