SOLUTION: How many gallons of 15% alcohol solution and 60% alcohol solution must be mixed to get 9 gallons of 30% alcohol solution?

 

Hi,

How many gallons of 15% alcohol solution and 60% alcohol solution must be mixed 

to get 9 gallons of 30% alcohol solution?

Mixing...............

 .60x + .15(9-x) = .30·9gal

       .45x = .15·9

          x = 3gal, amount of the 60% alcohol solution. 6gal of 15% alcohol solution

and...