determine if the two functions f and g are inverses of each other algebraically. If not, why?

f(x)=2x+3/4x-3 ; g(x) = 3x+3/4x-2

a:
no, (f o g)(x)= x+2/3
yes
no, (f o g)(x)=3x

f(x) = -x^3+2 ; g(x) = 3(cubedroot)x-2/2

a:
no, (f o g)(x)= x-14/8
yes
no, (fog)(x)=3-x/2

f(x)=-2x+4/2-5x ; g(x) = 4-2x/5-2x

a:
no, (f o g)(x)= -2x+6/3x-5
no, (f o g)(x)= -6x+6/3x-5
yes.

(the number say ex. g(x) = 4-2x / the "/" is a fraction unit. first unit over the other as provided. any help appreciated thank you <3)