Please solve with excel and show steps.Use the goal seek function. Answer these questions.

$6$a$.$ What is the value of $R$ at $6\mathrm{.}6\%$ interest to make all of the cash flow transactions balance out?

$6$b$.$ HOW do we know when all of the cash flows, in and out have been balanced?

$6c.$ If $R$ is $$25\mathrm{.}000$ what is the NEW interest rate we will need?