SOLUTION: how many gallons of a 70% antifreeze solution must be mixed with 100 gallons of 30% antifreeze to get a mixture that is 60% antifreeze?

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Question 415112: how many gallons of a 70% antifreeze solution must be mixed with 100 gallons of 30% antifreeze to get a mixture that is 60% antifreeze?
Answer by Tatiana_Stebko(1539) About Me  (Show Source):
You can put this solution on YOUR website!
Let x gallons of 70% antifreeze mix with 100 gallons of 30% antifreeze we'll get (100+x) gallons of new solution
in 100 gallons of 30% antifreeze is 0.3%2A100=30 gallons of antifreeze
in x gallons of 70% antifreeze is 0.7x gallons
in (100+x) gallons of 60% antifreeze is 0.6(100+x) gallons
Equation
30%2B0.7x=0.6%2A%28100%2Bx%29
30%2B0.7x=60%2B0.6x
0.1x=30
x=30%2F0.1
x=300 gallons of a 70% antifreeze solution must be mixed with 100 gallons of 30% antifreeze to get a mixture that is 60% antifreeze
Answer 300 gallons