Youve decided that you need to save enough for retirement so that you have an income $($before taxes$)$ of $$3500$ each month $($not including social security$).$ Assume youll live $30$ years after retirement and will earm about $5\mathrm{.}4\%$ annual intrest compounded monthly. How much moneu do you need to save by the start of your retirement? Suppose you decide to start saving for retirment at age $25$ and you plan to retire at $67.$ Assuming the same intrest scheme how much do you need to save each month to have the amount you found in part A at retirement?