A pharmacist has 5% saline (salt) solution and 20% saline solution. How much of each solution should be combined to create a bottle of 90mL of 10% saline solution?

Answer 1

Let F = the amount of 5% sol'n and T the amount of 20% sol'n

F + T = 90 => F = 90 - T

.05F + .2T = .1*90 => 5F + 20T = 900

Substitute

5(90 - T) + 20T = 900

You should be able to solve it from here.