What amount of a 75% acid solution must be mixed with a 25% solution to produce 500 mL of a 60% solution?

Step-by-step explanation:

If x is the volume of 75% solution, and y is the volume of 25% solution, then:

x + y = 500

0.75x + 0.25y = 0.60 (500)

Solving the system of equations:

0.75x + 0.25 (500 - x) = 0.60 (500)

0.75x + 125 - 0.25x = 300

0.50x = 175

x = 350

y = 150

You need 350 mL of 75% solution and 150 mL of 25% solution.