A shopkeeper offers successive discounts of 20% and 25% on the marked price of an article and gets a profit of 20%. If he wants to make 40% profit, the percentage by which the marked price is to be increased is

Let say,marked price is m and cost price is c.

So,after two successive discount ,he will sell it for = 0.8×0.75m=0.6m Rs.

Profit=(0.6m-c) Rs.

So, 0.6m-c=.2c

or,1.2c=0.6m

or, c/m=1/2.

Let say ,c=k and m=2k.

if he wants to profit 40% then selling price would become (1.4×k)=1.4k.

let say marked price should increase by n%.

then, (2k(1+n%)0.8×0.75-k)=0.4k.

or,1.2(1+n%)k=1.4k.

or,1+n%=14/12.

or,1+n%=7/6.

or,n%=1/6.

or,n=100/6=50/3.

C is correct choice.