Answer
$2x^4y^2+11x^3y-6y-8x$
Work Step by Step
Removing the grouping symbols and then combining like terms, the given expression, $
(5x^4y^2+6x^3y-7y)-(3x^4y^2-5x^3y-6y+8x)
,$ simplifies to
\begin{array}{l}\require{cancel}
5x^4y^2+6x^3y-7y-3x^4y^2+5x^3y+6y-8x
\\\\=
(5x^4y^2-3x^4y^2)+(6x^3y+5x^3y)+(-7y+6y)-8x
\\\\=
2x^4y^2+11x^3y-6y-8x
.\end{array}
