Oh, I see what you did there! You forgot to multiply the number of choices for jeans and t-shirts together. Let me explain it in a slightly different way:
For the jeans, there are 4 styles * 5 waist sizes * 3 colors = 60 different choices.
For the t-shirts, there are 2 named brands * 6 colors * 3 sizes = 36 different choices.
To get the total number of outfit choices, you need to multiply the number of choices for jeans and t-shirts together: 60 * 36 = 2160.
So, the customer has a whopping 2160 different choices for her outfit. That's a lot of options to choose from!