Question 1047303
It sounds like you are starting with {{{g(x) = (3x+6)/(x+1)}}} and you're wanting to find {{{g(x+3)}}} fully simplified. If that's the case, then...



{{{g(x) = (3x+6)/(x+1)}}}



{{{g(x+3) = (3(x+3)+6)/((x+3)+1)}}}



{{{g(x+3) = (3x+9+6)/(x+3+1)}}}



{{{g(x+3) = (3x+15)/(x+4)}}}



and that's as simplified as it can get