Arun bought toffees at 6 for a rupee. How many for a rupee he should sell to gain 20%?

Answer: Option D

CP for one toffee = $$\frac{100}{6}$$
SP will be 20% above the CP.
So,
SP for one toffee = $$\frac{100}{6}\times 1.2=\frac{100}{5}=20$$
Thus, He should sell 5 toffee for Rs. 1 (100 paise)