Answer:
20*4=80 + 20 = 100
Explanation:
I can wear five different shirts, for each shirt, I can have any of four different pants.
That’s 5*4=20 outfits.
But I can wear two shirts, I often do. For each of five shirts worn underneath, there are four shirts I can wear over that, so there are twenty shirt pairings, and again, four different pants to wear with each pair, that’s 20*4=80 + 20 = 100