Purchase value is less than fair value or market value.

Person A hold a land with Market value of Rs. 40 lakhs & purchase value of Rs 20 lakhs in his sale deed done 3 yrs back.

Now Planing to sell it Person B whose Market value is Rs.60 lakhs but with Purchase value of Rs.45 lakhs. Person B is ok to pay styamp duty as per the govt. fair valu or market value .

what are the tax implications to person A as well as Person B.