Question 1133860
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Here's an alternative to the traditional algebraic method for solving mixture problems like this involving two ingredients.  If you understand it, it will get you to the answer much faster and with far less work.<br>
(1) Think of starting with the 21% alloy and adding the 36% alloy until the mixture is 33% copper.
(2) 33% is 4/5 of the way from 21% to 36%.  (33-21=12; 36-21=15; 12/15 = 4/5).
(3) That means 4/5 of the mixture must be what you are adding -- the 36% alloy.<br>
So 4/5 of the total 44 pounds, or 35.2 pounds, is the 36% alloy and the other 8.8 pounds is the 21% alloy.