A vendor bought toffees at 6 for a rupee. How many for a rupee must he sell to gain 20%?
Answer: (c) 5
C P of 6 toffee = Rs. 1
Therefore, cost of one toffee = 1/6
vendor want 20% gain
then S P of on toffee = 1 x 120/6 x 100 = 1/5
Hence, he sell 5 toffee at 1 rupee.