Question

The profit on a watch is 15% of the cost price. If the profit is $150, find
(i) the cost price,
(ii) the selling price
of the watch.​

Answer 1

Let the CP of the watch be Rs.x. 

Case I,

Therefore, SP = 120x100=Rs.6x5120x100=Rs.6x5

Case II, 

CP = Rs.(x - 100) 

SP = Rs. (6x5−100)(6x5−100)

Profit = (6x5−x)=Rs.x5(6x5−x)=Rs.x5

Therefore, x5x−100×100=25x5x−100×100=25

=> 25x - 2500 = 20x

=> 5x = 2500

=> x = 2500525005 = Rs.500