A man brought toffees at 6 for a rupee. How many toffees for a rupee must he sell to gain in 50%.?

CP of 6 toffees = ₹ 1,
SP of 6 toffees = 150% of 1 = 150/100 = 3/2
∵ For ₹ 3/2, the number of toffees sold = 6
∴ For ₹ 1, the number of toffees sold = 6 x (2/3) = 4