please show what formula you used, and please solve it if you know what formula should use, and please don't copy from other answers cause those are not right!!

1. While she was travelling, Zainab took advantage of the convenience of cash withdrawals on her credit card since her Canadian debit card wasn't accepted in the country she was in.According to her travel budget she withdrew $150 every day for food, activities and shopping for 21 days.When she got home, on the 21st day, she checked her credit card bill on-line and it showed that she had been charged interest already even though her payment wasn't past due.It turns out that interest is compounded daily on cash withdrawals, from the day the cash is withdrawn.

If the interest rate on cash withdrawals is 28%, what was her total bill when she got home?[1]

What would be the total interest paid?[2]