a$.$ Someone in the $36$ percent tax bracket can earn $9$ percent annually on her investments in a tax$-$exempt IRA account. What will be the value of a one$-$time $$10,000$ investment in $5$ years? $10$ years? $20$ years?

b$.$ Suppose the preceding $9$ percent return is taxable rather than tax$-$deferred and the taxes are paid annually. What will be the after$-$tax value of her $$10,000$ investment after $5,10,$ and $20$ years?