Answer
$-2x^{3}+2x^{2}+9x-5$
Work Step by Step
The sum of $(2x^{2}+4x-7)$ and ($-5x^{3}-2x-3)$ is
$ \begin{array}{lllll}
& & 2x^{2} & +4x & -7\\
+( & -5x^{3} & & -2x & -3)\\
\hline & & & & \\
= & -5x^{3} & +2x^{2} & +2x & -10\\
& & & &
\end{array} $
Subtract $(-3x^{3}-7x+5)$ from the above sum;
$ \begin{array}{lllll}
& -5x^{3} & +2x^{2} & +2x & -10\\
-( & -3x^{3} & & -7x & +5)\\
\hline & & & & \\
= & -2x^{3} & +2x^{2} & +9x & -5
\end{array} $
