Question 306999
Solution X is 40% acid and solution Y is 85% acid. How much of each is needed to make a 90 Liters of a solution that is 70% acid?

solution X - 40% 
solution y -85%

Let quantity of X be x liters
Quantity of Y will be 90-x liters

Total quantity required = x+90 with cocentration of 70%

Concentration of X in the mixture = 0.4x
Concentration of Y in the mixture = 0.85(90-x)
Concentration of mix= 0.7(90+x)

0.4x+0.85(90-x)= 0.7(x+90)

0.4x+76.5-0.85x = 0.7x+63

-1.15x=-13.5

x=11.7 liters
Balance will be solution Y=9.3 liters