Given the following tax structure, what minimum tax would need to be assessed on Shameika to make the tax progressive with respect to average tax rates?

$\backslash$table$[[$Taxp$,$Salary,$\backslash$table$[[$Muni$-$Bond$],[$Interest$]],$Total Tax$],[$Mihwah$,$$$20,000,$$$8,150,$$$1,680$