How many gallons of 25% alcohol and 5% alcohol should be mixed to obtain 20 gallon of 24% alcohol?

19 gallons of 25% alcohol and 1 gallon of 5% alcohol

Step-by-step explanation:

If x is the gallons of 25% alcohol, and y is the gallons of 5% alcohol, then:

x + y = 20

0.25x + 0.05y = 0.24 (20)

Solve the system of equations using substitution:

0.25x + 0.05 (20 - x) = 0.24 (20)

0.25x + 1 - 0.05x = 4.8

0.2x = 3.8

x = 19

y = 20 - x

y = 1

You need 19 gallons of 25% alcohol and 1 gallon of 5% alcohol.