By selling 12 toffees for a rupee, a man loses 20%. How many for a rupee should be sell to get a gain of 20%?

A. 5
B. 8
C. 10
D. 15
Explanation:
Let S.P. of 12 toffees be Rs. x.
Then, 80:1 = 120:x or x = 120/180 = 3/2
For Rs. 3/2, toffees sold = 12.
For Re. 1, toffees sold = 12 * 2/3 = 8