$3.)$ You currently have saved $$12,647$ in a brokerage account and you plan to deposit $$2,500$ at the end of every year until your account totals $$50,000.$ You expect to earn $8\%$ annually on the account. How many years will it take you to reach your goal?

$4.)$ You have just made your first $$5,500$ contribution to your retirement account. Assuming you earn a return of $10\%$ per year and make no additional contributions, what will your account be worth when you retire in $45$ years? What if you wait $10$ years before contributing?