Question

Given that f(x) = 5x − 10 and g(x) = x + 3, solve for f(g(x)) when x = −1.

Answer 1

just substitute g(x) = x+3 in f(g(x)) and go from there........

Answer 2

what is g(-1)

Answer 3

or you can do like this.
f(g(x))=f(x+3)=5(x+3)-10
simplify and then find the solution at x=-1