Let the no. of liters of 5% solution= x
So...the no. of liters of 25% solution is (10 - x)
So.....we have this
5 % solution * amt + 25% solution * amt = 10% solution * 10 liters
.05 x + .25(10 - x) = .10 * 10 simplify
05x + 2.5 - .25x + 1
-.20x + 2.5 = 1 subtract 2.5 from both sides
-.20x = - 1.5 divide both sides by .20
x = 7.5 liters of 5% solution
And
10 - x = 10 - 7.5 = 2.5 liters of 25% solution
Answer " C "