Rahul wants to sell a watch at a profit of 20%. He bought it for 10% less and sold it at Rs. 30 less, but still, he gained 20%. The  cost price of the watch ?

250

            C.P.     :     Profit %    :     S.P

1st  :     100     :         20        :     120

2nd :      90      :         20        :     108

Here,

⇒ Difference b/w SP₁ and SP₂ = 12R

⇒ 12R = 30 (given)

⇒ 1R = 2.5

⇒ Initial C.P. = 100R = 100 × 2.5 = 250