Math
posted by Chanelle .
Suppose that you have a supply of a 25% solution of alcohol and a 75% solution of alcohol. How many quarts of each should be mixed to produce 90 quarts that is 60% alcohol?

work with the amount of alcohol in each part. It has to add up to the total alcohol.
.25x + .75(90x) = .60(90)
x = 27
so, 27 qt @ 25% and 63 qt @ 75% 
Thank you,and how did you get come up with the equation?

Thank you,and how did set up the equation?

If you let x be the amount of 25% solution, then .25x is the amount of alcohol in that solutions.
Since there are 90 qts in all, 90x is the amount of the 75% solution. .75(90x) is the amount of alcohol in that solution.
Add up the two amounts of alcohol, and it must equal the amount of alcohol in 90 qts of 60% solution.
Tadaa 
Thanks