Question 627311
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Hi,
how much of an alloy{{{highlight(x)}}} that is 30% copper should be mixed with 200oz of an alloy that is 90% copper 
in order to get an alloy that is 70% copper
    copper + copper = copper
 {{{.30x + .90*200oz = .70(200+x)
            {{{.20*200 = .40x}}}
                   100oz = x

Note:  30oz + 180oz =  210oz                      
Set Up on ALL mixture problems is to have the same amount of the <u>key ingredient</u> on both sides of the EQ