A chemist has one solution that is 25% salt and 75% water and another solution that is only 5% salt. How many milliliters of each should the chemist use to make 1400 ml of a solution that is 10% salt.

Let x = number if mL of the first solution. 1400-x = number of mL of second solution.

Equation: (1/4) x + (1/20) (1400-x) = 140

(1/4) x + 70 - (1/20) x = 140

(4/20) x = 70

(1/5) x = 70

x = 350

350 mL of first

1050 mL of second

10% of 1400 milliliters is 140 milliliters, so 140 milliliters is Salt