A woman borrows £180,000 from a bank at 10% per annum compound interest. She repays 50,000 at the end of each year. How much does she still owe at the end of 4 years?

Answer 1

at end of year 1: 180000 * 1.10 - 50000 = 148,000
repeat for the next 3 years.
Or, I'm sure you have a handy formula.