Question

a shopkeeper purchased a clock for rs 300 and sells it a gain of 20 percent find sp of a clock

Answer 1

Here's ur answer........

Answer 2

lets compare:
if the clock was  purchased for 100 then its sp was 120 (20% gain)
same way if the clock was purchased for 300 then sp was x(20% gain)

now cross  multiplication:

100         120
300         x

100x=300*120
100x=36000
x=      36000/100
x= 360

the sp of the clock is rs 360