A 25% acid solution is mixed with a 75% acid solution to get 60 liters of a 45% solution. How many liters of the 25% solution are needed?

24 liters

30 liters

36 liters

Let volume of 25% solution = x and vol of 75% = y liters so we have:-

x + y = 60 ... (1)

0.25x + 0.75y = 0.45*60 = 27

multiply second equation by 4:-

x + 3y = 108 ... (2)

subtract (1) from (2) : -

2y = 48

y = 24 This is the volume of 75% solution

Volume of 25% solution = 60 - 24 = 36 liters Answer