$(3$ pts$.)$ Use the present value PV spreadsheet formula to calculate the deposit needed for each of the following investments. Show your work by writing down what you typed into the spreadsheet.

a$)4\%$ APR compounded yearly, $12$ years, future value $$6000$

b$)3\mathrm{.}5\%$ APR compounded semi$-$annually, $5$ years, future value $$2000$