A chemical company makes two brands of antifreeze. The first brand is 70% pure antifreeze, and the second brand is 90% pure antifreeze. In order to obtain

Question

A chemical company makes two brands of antifreeze. The first brand is
70%
pure antifreeze, and the second brand is
90%
pure antifreeze. In order to obtain
140
gallons of a mixture that contains
75%
pure antifreeze, how many gallons of each brand of antifreeze must be used?

Answer 1

Because we know the total amount of solution is 140 gallons, we can say the two components have volumes x and (140-x).

 

70x + 90 (140 - x) = 75 * 140

 

70x + 12600 - 90x = 10500

 

-20x = -2100

 

x = 105

 

So we must use 105 gallons of the 70% solution and 140-105 = 35 gallons of the 90% solution.