Question

(8xy)-(-2xz)+(-9xy)-(+2xz)

Answer 1

$8xy-\left(-2xz\right)+\left(-9xy\right)-\left(+2xz\right)\\8xy+2xz-9xy-2xz\\8xy-9xy+2xz-2xz\\xy\cdot \left(8-9\right)+xz\cdot \left(2-2\right)\\xy\cdot \left(-1\right)+xz\cdot 0\\\boxed{\bold{-xy}}$