The difference between CP and SP is Rs 240, and there is a 20% profit.
Since there is a profit, the selling price is greater than the cost price:
SP−CP=240
A profit of 20% means:
Profit =20% of CP
Profit =10020×CP
Profit =0.2×CP
Since Profit =SP−CP, we have:
0.2×CP=240
CP=0.2240
CP=1200
Using SP−CP=240:
SP=CP+240
SP=1200+240
SP=1440
Therefore, the selling price is Rs 1440.