Here's written and evaluated expressions:

Hint:

f(x)=ax+b

g(x)=cx+d

(f+g)(x) = f(x)+g(x) = ax+b + cx + d

(f-g)(x) = f(x)+g(x) = ax+b -( cx + d) = ax+b - cx - d

(f.g)(x) = f(x)*g(x) =( ax+b )(cx + d)