Simplify -3xy^2+2x^2y+8xy^2-2xy-3xy^2+xy

$- 3 x y^{2} + 2 x^{2} y + 8 x y^{2} - 2 x y - 3 x y^{2} + x y$

Add $- 3 x y^{2}$ and $8 x y^{2}$ .

$5 x y^{2} + 2 x^{2} y - 2 x y - 3 x y^{2} + x y$

Subtract $3 x y^{2}$ from $5 x y^{2}$ .

$2 x y^{2} + 2 x^{2} y - 2 x y + x y$

Add $- 2 x y$ and $x y$ .

$2 x y^{2} + 2 x^{2} y - x y$