Answer:
72%
Explanation:
As the T-shirts have 20% off and Juanita would get an extra 10% off the sale price, the additional discount would be over the price with the 20% off included. This means that the sale price is the 80% of the normal price and an additional 10% over that 80% would be:
80*10%= 8
80%-8%= 72%
This means that Juanita would have to pay the 72% percent of the regular price of the T-shirt as the total discount would be 28% off.