Answer
$14x^2y-10xy-9xy^2$
Work Step by Step
By removing first the grouping symbols, the given expression, $ (5x^2y-8xy-6xy^2)-(2xy-9x^2y+3xy^2) ,$ is equivalent to \begin{align*}
&
(5x^2y-8xy-6xy^2)-2xy+9x^2y-3xy^2 &(\text{alter the signs})
\\&
5x^2y-8xy-6xy^2-2xy+9x^2y-3xy^2 .\end{align*}
By combining the like terms next, the expression above is equivalent to \begin{align*} & (5x^2y+9x^2y)+(-8xy-2xy)+(-6xy^2-3xy^2)
\\&=
14x^2y-10xy-9xy^2
.\end{align*} Hence, the expression $(5x^2y-8xy-6xy^2)-(2xy-9x^2y+3xy^2)$ simplifies to $14x^2y-10xy-9xy^2$.
