The left hand side are examples and the right are the questions! Could somebody pls help me with questions D and E

At the beginning of 1974/75,2 years a man invested #2000 in a bank at 12.5% compound interest, if it degree #650 at the end of each two years to pay his son's school fees, after payment of interest to pay his son's school fees, how much did he have left at the beginning of the 1978/79 school year?

What’s the answer ? use the picture to see the problem

The holiday party will cost $160 if 8 people attend.if there are 40 people who attend the party, how much will the holiday party cost