Using the facts in the previous problem, what minimum tax would need to be assessed on Shameika

Question:

Using the facts in the previous problem, what minimum tax would need to be assessed on Shameika to make the tax progressive with respect to effective tax rates?
In previous problem,
Taxpayer____ Salary ______Muni-Bond Interest _____ Total Tax
Mihwah ....... 10,000 .................10,000 ........................600
Shameika ...... 50,000 .................30,000 ........................???