Answer:
0.018 = 1.8%
Explanation:
There are 7 choices of shirt. Each of those can be paired with any of the 8 choices of pants, for a total of 7×8 = 56 possible pairings of shirt and pants.
Of those, only one pairing is green/green. So, assuming all pairings are equally likely when getting dressed in the dark, the probability of an all-green outfit is 1/56 ≈ 0.01786 ≈ 1.8%.