Find the inverse of the linear transformation $$\begin{array}{r@{}r@{}r@{}r} y_1 & = & 3 x_1 & - 1 x_2 \cr y_2 & = & -11 x_1 & + 4 x_2 \end{array}$$
$x_1=$ $y_1+$ $y_2$,
$x_2=$ $y_1+$ $y_2$.