1. The problem statement, all variables and given/known data A mortgage is taken out for £80,000. It is to be paid by annual instalments of 5000with the first payment being made at the end of the first year that the mortgage was taken out. Interest of 4% is then charged on any outstanding debt. Find the total time taken to pay off the mortgage. 2. Relevant equations Sn=a(r^n-1)/r-1 3. The attempt at a solution I have no idea here can someone please point me in the right direction, thanks!