i need help with this math problem?

Published November 7, 2010

Question by Scott S: i need help with this math problem?
“A mechanic has some antifreeze that is 40% alcohol and another type that is 60% alcohol. She wishes to make 1000 gallons of antifreeze that is 48% alcohol. How much should she use.” All i need is the set up. someone please help

Best answer:

Answer by MoonRose
Let x be the number of gallons of the 40% alcohol antifreeze and y be the number of gallons of the 60% alcohol antifreeze. There are going to be 1000 gallons of antifreeze total, so x + y = 1000. The amount of alcohol is the total number of gallons multiplied by the percentage. Therefore, the amount of alcohol in the 40% alcohol antifreeze is 0.4x gallons and the amount of alcohol in the 60% alcohol antifreeze is 0.6y gallons. This needs to add up to the 48% alcohol in the 1000 gallons of antifreeze, which is 0.48(1000) = 480 gallons, so 0.4x + 0.6y = 480.

x + y = 1000
0.4x + 0.6y = 480

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