Assume that your parents wanted to have $ $100000$ saved for college by your $18$th birthday and they started saving on your first birthday. They saved the same amount each year on your birthday and earned $9\mathrm{.}0\%$ per year on their investments.

a$.$ How much would they have to save each year to reach their$$ goal?

b$.$ If they think you will take five years instead of four to graduate and decide to have $ $140000$ saved just in$$ case, how much would they have to save each year to reach their new$$ goal?