Question 56064
{{{f(x) = 2x + 3}}}
{{{g(x) = (x - 3)/2}}}

You can do it the hard way:

{{{f(g(-5)) = 2((-5-3)/2) + 3}}}
{{{f(g(-5)) = 2(-8/2) + 3}}}
{{{f(g(-5)) = 2*-4 + 3}}}
{{{f(g(-5)) = -8 + 3}}}
{{{f(g(-5)) = -5}}}

Or the easy way:

{{{f(g(x)) = cross(2)((x-cross(3))/cross(2)) + cross(3)}}}
{{{f(g(x)) = x}}}