Question 1160380
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...,bottles of developer, one a 70% solution, the other, 20% solution. How much developer should he take from each bottle to make 10 ounces of 50% solution?
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x of 70%
10-x of 20%


{{{70x+20(10-x)=50*10}}}

-

{{{7x+2(10-x)=5*10}}}

{{{7x+2*10-2x=5*10}}}

{{{(7-2)x+2*10=5*10}}}

{{{(7-2)x=10(5-2)}}}

{{{highlight_green(x=10((5-2)/(7-2)))}}}


{{{highlight(x=6)}}}------------"ounces" of the 70% developer


{{{highlight(4)}}}------------"ounces" of the 20% developer