Raghu bought toffees at 10 for a rupee. How many for a rupee must he sell to gain 400%?

Correct option is A

Given:

Cost Price (CP) = ₹1 for 10 toffees

So CP of 1 toffee = ₹0.10

Solution:

If gain is 400%, then

Selling Price (SP) = CP + 400%  of CP = $$5 \times CP$$​​

So SP of 1 toffee = ₹0.10 × 5 = ₹0.50

Now, 

Number of toffees = $$\frac{1}{\text{SP per toffee}}$$​​

​$$= \frac{1}{0.5} = 2$$​​