Ella borrowed $$20,000$ at a $6\%$ annual rate of interest to be repaid over five

years. The loan is amortized into five equal, annual, end$-$of$-$year payments.

a$.$ Write down the formula with numerical inputs for calculating the end$-$of$-$year loan payment $($An example of a formula with numerical inputs: $4000/(1+0\mathrm{.}7)^3).$

b$.$ Calculate the annual, end$-$of$-$year loan payment.

c$.$ What are interest payments in years $1,2,$ and $3?$

d$.$ What is the ending loan principle at the end of year $3?$