[tex]General\ equation\ for\ line\ in\ slope\ intercept\ form:\\\\y=ax+b\\\\To\ find\ a\ and\ b\ substitude\ points\ (3,-5),\ (-5,3)\ into\ equation\\\\
\left \{ {{-5=3a+b}\ \ \ \ \atop {3=-5a+b\ |*-1}} \right.\\\\ \left \{ {{-5=3a+b} \atop {-3=5a-b}} \right. \\+----\\\\-8=8a\ \ \ |:8\\a=-1\\\\-5=3\cdot(-1)+b\\-5=-3+b\\-5+3=b\\b=-2\\\\y=-x-2[/tex]