The 80 liters of mixture contains 40% of Petrol and 60% of Kerosene. In how much liters of Petrol added to the mixture

The 80 liters of mixture contains 40% of Petrol and 60% of Kerosene. In how much liters of Petrol added to the mixture, if the percentage of the kerosene in the mixture becomes 40%?

A.30 liters

B.40 liters

C.20 liters

D.50 liters

E.None of these

Sol:

Petrol = 40/100 * 80 = 32

Kerosene = 60/100 * 80 = 48

(32 + x)/48 = 60/40

2 * (32 + x) = 48 * 3

64 + 2x = 144

x = 40 liters