Banker's Discount - General Questions

The banker's discount on a sum is Rs. 1,131 and the true discount is Rs. 870. What is the sum due?

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. 14,100 due 8 months hence at 4% per annum?

The true discount on a bill due 1 year(s) hence at 10% per annum is Rs. 240. 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?