$(8$ points$)$ Answer the following two questions. Make sure you draw a timeline for each part.

a$.(4$ points$)$ A businessman wants to buy a truck. The dealer offers to sell the truck for either $$120,000$ now, or six yearly payments of $$25,000,$ with the first payment one year after the purchase of the truck. What is the yearly interest rate being offered by the dealer $($to the customer$)?$

b$.(4$ points$)$ Faisal has $$15,000$ in his savings account and can save anditional $$5000$ per year. If interest rates are $12\%$ per year, how long will it take his savings to grow to $$58,200?$