Question 650807
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Hi,
What quantity{{{highlight(x)}}} of 75 percent acid solution must be mixed with a 30 percent solution 
to produce 135 mL of a 50 percent solution? 
   acid  = acid
 {{{.75x + .30(135-x) = .50*135}}}
                 .45x = .20·135
                    x = .20·135/.45