Banker's Discount - General Questions

The true discount on a bill due 3 year(s) hence at 12% per annum is Rs. 252. What is the banker's gain?

The true discount on a bill due 1 year(s) hence at 5% per annum is Rs. 120. What is the banker's gain?

The true discount on a bill due 2 year(s) hence at 10% per annum is Rs. 220. What is the banker's gain?

The banker's discount on a sum is Rs. 1,287 and the true discount is Rs. 990. What is the sum due?

The true discount on a bill due 3 year(s) hence at 5% per annum is Rs. 240. What is the banker's gain?