Question 395269
A chemist needs a 26% acid mixture, but his lab only has 20% and 35% solutions. If he needs a total of 80 liters of the 26% solution, how much of each percent acid does he need? 
I was thinking:
.20(x) + .35(y) = .26(80) 
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You can use x & y
Your equation is right, and it's the way to do it.
The 2nd eqn is 
x + y = 80
You can finish it, I think.