Answer:
The answer to your question is 20%
Explanation:
Think of it as a simple addition problem and take the percentages out of it. Since we want to know what the total discount of the shirt is we could take the original discount of the store (10% or 10) and then we could take your coupon for (10% or 10) and add them together to get the total discount of the shirt. That's a really exaggerated way to put it so think of it like this:
10%+10%= 20%