Помогите решить систему 1/х-1/у=-4/5 х-у=4

[latex] \left \{ {{5y-5x=-4xy} \atop {x-y=4}} \right. [/latex] [latex] \left \{ {{5y-20-5y=(-16-4y)*y} \atop {x=4+y}} \right. [/latex] [latex] \left \{ {{4 y^{2}+16y-20=0} \atop {x=4+y}} \right. [/latex] [latex]D= \sqrt{36} = 6^{2} [/latex] [latex]y_{1} = 1 y_{2} = -5[/latex] [latex] x_{1} =5 x_{2} =-1[/latex]