Answer
See below for answer
Work Step by Step
a. f∘g is defined is the function of g(x), which is $f(g(x))$
Domain is defined by all real numbers x in the domain of g so that g(x) is contained within the domain of f
b. $g(a) = b$ $f(b) = c$
$(f∘g) (a) = f(g(a)) = f(b) = c$
Thus $ (f∘g) (a) = c$
