Помогите пожалуйста) нужно упростить

Решите задачу:

$\frac{ {x}^{3} - {y}^{3} }{x - y} \div ( {x}^{2} - {y}^{2} ) - \frac{2x}{x - y} + \frac{xy}{ {x}^{2} - {y}^{2} } = \frac{(x - y)( {x}^{2} + xy + {y}^{2} ) }{x - y} \div ( {x}^{2} - {y}^{2} ) - \frac{2x(x + y)}{(x - y)(x + y)} + \frac{xy}{ {x}^{2} - {y}^{2} } = \frac{ {x}^{2} + xy + {y}^{2} }{ {x}^{2} - {y}^{2} } - \frac{2 {x}^{2} + 2xy}{ {x}^{2} - {y}^{2} } + \frac{xy}{ {x}^{2} - {y}^{2} } = \frac{ {x}^{2} + xy + {y}^{2} - 2 {x}^{2} - 2xy + xy}{ {x}^{2} - {y}^{2} } = \frac{ - {x}^{2} + {y}^{2} }{ {x}^{2} - {y}^{2} } = \frac{ - ( {x}^{2} - {y}^{2} )}{ {x}^{2} - {y}^{2} } = - 1$