Let f(2)=3, g(2)=4, f'(2)=5, g'(2)=6, f'(3)=7, g'(3)=8, etc.

find (f∘g)′(2)

(f∘g) = f(g)

so, (f∘g)' = df/dg * dg/dx
(f∘g)(2) = f'(g(2)) * g'(2)
= f'(4) * g'(2)
= 8*6
= 48

if you're still unsure, use an example

f(x) = sin(x)
g(x) = x^2

(f∘g)(x) = sin(x^2)
(f∘g)' = cos(x^2) * 2x
and the logic above makes sense