Ametallurgist has an alloy with 10% titanium and an alloy with 20% titanium. he needs 100 grams of an alloy with 17% titanium. how much of each alloy should be mixed to attain the 100 grams of alloy with 17% titanium?

now, notice, we use the decimal format for the percent, namely 17% is 17/100 or 0.17 and so on

so....  we know, whatever "x" and "y" is, they must add up to 100 grams
thus    x + y = 100

and whatever the concentrated amount is, it must add up to 17 grams for the composition

thus   0.1x + 0.2y = 17



solve for "x", to see how much is needed of the 10% alloy

what about "y"? well, y = 100 - x