Answer
$105x+9$
Work Step by Step
Original expression: $4+(105x+5)$
Combine like terms. 4 and 5 are the only terms we can combine because there are no other variables in the expression. We can add these because of the associative property of addition.
$5+4=9$
The expression should now look like this: $105x+9$
It is impossible to simplify this further because all like terms have already been combined. So your final, simplified answer is $105x+9$.