calculus
posted by Julie .
What quantity of 65 per cent acid solution must be mixed with a 25 percent solution to produce 384 mL of a 50 per cent solution?

Let there be x mL of 65% solution and y mL of 25% solution.
x + y = 384
Amount of acid:
0.50*384 = 192 = 0.65 x + 0.25 y
768 = 2.6 x + y
Subtract the first equation from the third.
1.6 x = 384
x = 240 mL
y = 144 mL