[tex]\left\{\begin{array}{ccc}x-y=11&\to x=y+11\\x\cdot y=42\end{array}\right\\\\(y+11)y=42\\y^2+11y-42=0\\y^2+14y-3y-42=0\\y(y+14)-3(y+14)=0\\(y+14)(y-3)=0\iff y=-14\ \vee\ y=3\\\\x=-14+11=-3\ \vee\ x=3+11=14\\\\Answer:-3\ and\ -14\ or\ 14\ and\ 3[/tex]