Answer
$8m^3-3m-7$
Work Step by Step
By combining like terms, the given expression, $
(4m^3-7m^2+m-5)+(4m^3+7m^2-4m-2)
$, simplifies to
\begin{array}{l}
(4m^3+4m^3)+(-7m^2+7m^2)+(m-4m)+(-5-2)
\\\\=
8m^3+0m^2-3m-7
\\\\=
8m^3-3m-7
.\end{array}