A car mechanic purchased four old cars for Rs. 1 lakh. He spent total 2 lakh in the maintenance and repairing of these four cars. what is the average sale price of the rest three cars to get 50% total profit if he has already sold one of the four cars at Rs. 1.2 lakh?

Total cost of 4 cars =  1+2 = 3 lakh

Total S.P of 4 cars = 3 x 1.5 = 4.5 lakh   ( $Since S.P = \frac{100 + Gain\%}{100} x C.P$)

 S.P of 1 car = 1.2 lakh 

S.P of rest 3 cars = 4.5 - 1.2 = 3.3 lakh

 Average S.P of all the 3 cars = 1.1 lakh