Answer:
C. 18x+9y
Step-by-step explanation:
I think its the third one, C. Hope this helps!
144 lol
9514 1404 393
24
The number of permutations of 4 items is 4! = 24.
math, maht, mtah, mtha, mhat, mhta,
amth, amht, atmh, athm, ahmt, ahtm,
tmah, tmha, tamh, tahm, thma, tham,
hmat, hmta, hamt, hatm, htma, htam