Marked price = Rs 20.
Discount on marked price = 20%
So selling price = 20 -20%of 20 = 20 - (20/100)(20)=20-0.2*20=20-4= Rs 16
Let C,P, = Rs x. Selling price = Rs 16.
Profit = 12%.
It means (16-x)/x *100 = 12% or (16-x)/x = 0.12
16-x = 0.12x => 1.12x = 16=> x = 16/1.12 = Rs 14.29
Answer: Rs 14.29