Elki would like to invest $50,000 in tax-exempt securities. He now has the money invested in a…

Elki would like to invest $50,000 in tax-exempt securities.
He now has the money invested in a certificate of deposit that pays 5.75%
annually. What rate of interest would the tax-exempt security have to pay to
result in a greater return on Elki’s investment than the certificate of
deposit? Work the problem assuming that Elki’s marginal tax rate is 15%, 25%,
28%, and 33%.