Hi,
f°g means : apply first g then f . so calculate "g" and then use result as "x" in f.
g°f means : you apply first f then g
so : f°g = 2(3x²-x) -5 = 6x²-2x- 5
To improve in math, you need practice. have a try with g°f :)
give the answer in comments, and I will tell you if you are correct.
good luck.
