Question

How much 25% antifreeze and 50% antifreeze should be combined to give 40 gallons of 30% antifreeze?

Answer 1

32 gallons of 25% and 8 gallons of 50%

Explanation:

let a gallons of 25% antifreeze and b gallons of 50% antifreeze be needed to get 40 gallons of 30% antifreeze .
thus , `a+b=40`
`30 = 25a/40 + 50b/40`
`48 = a + 2b`
now , `a=40-b`
`48 = 40 -b +2b`
therefore , `b= 8 gallons`
`a= 40-8 = 32 gallons`