Question 398021
    A lab needs to make 500L of a 34% acid solution for a customer. The lab has 25% and 50% acid solutions available to make the order. How many litres of each should be mixed to make the 34% solution? I can't figure out what the two equations are to solve the problem.
The total amount of liters required is 500. (This is the first equation)
let x = liters of the 25% solution
then 500-x = liters of the 50% solution
.25x = amount of acid in the 25% solution
.50(500-x) = amount of acid in the 50% solution
.34(500) = amount of acid in the mixture with a 34% solution

The the total amt of acid in the two solutions added together is equal to the amount of acid in the final mixture. (This is the second equation)

.25x+.50(500-x)=.34(500)
25x+50(500-x)=34(500)
25x+25000-50x=17000
25x=8000
x=320 liters
500-x=180 liters 

ans: 320 liters of the 25% solution must be mixed with 180 liters of the 50% solution to get 500 liters of a 34% solution