A person purchases toffees at Rs 10 per dozen and sells them at Rs 12 for every 10 toffees Find the gain in percentage?

Cost of 12 toffees = Rs 10

Revenue for 10 toffees = Rs 12

so revenue for 12 toffees = Rs 14.40

Gain = Rs 4.40

Percentage gain = 100*4.40/10 = 44%