How many gallons of a 70% antifreeze solution must be mixed with 90 galoons of 20% antifreeze to get a mixture that is 60% antifreeze?

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Answer 1 · 2018-06-18T09:16:44

#360# gallons of 70% solution

Let the unknown volume be #x# giving:

#[70%xx x]+[20%xx90]=60%xx(90+x)#

#[70/100xx x]+[20/100xx90]=60/100xx(90+x)#

Multiply both sides by 100

#70x+1800= 5400+60x#

#10x=3600#

#x=360#
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#color(blue)("Check LHS against RHS")#

#[70%xx x]+[20%xx90]=60%xx(90+x)#

#252+18=270#

#270=270#