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?

What is the banker's discount on a bill of Rs. 9,300 due 3 months hence at 6% per annum?

The banker's discount on a sum is Rs. 357.12 and the true discount is Rs. 288. What is the sum due?

What is the banker's discount on a bill of Rs. 7,100 due 6 months hence at 4% per annum?

The banker's discount on a sum is Rs. 1,126.08 and the true discount is Rs. 828. What is the sum due?