Question 252839
An airplane begins a flight with a total of 36.0 gal. of fuel stored in two separate wing tanks. During the flight, 25.0% of the fuel in one tank is used, and in the other tank, 37.5% of the fuel is used. If the total fuel used is 11.2 gal., find the amounts x and y stored in each tank. 
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Start with 36 gal in 2 tanks.
Use 11.2 gallons from both tanks.
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Equation:
0.25x + 0.375y = 11.2
x+y = 36
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Modify the equations:
250x + 375y = 11200
250x + 250y = 36*250
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Subtract the 2nd Eq. from the 1st and solve for "y":
125y = 2200
y = 17.6 gallons (amount in the 2nd tank)
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Since x + y = 36, x = 36-17.6 = 18.4 gallons (amount in the 1st tank)
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Cheers,
Stan H.