A25% 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

Cd is the perpendicular bisector of both xy and st, and cy=20.find xy