Problems $4 I-48$. compute the image under $T$ of $\overrightarrow{\mathrm{u}}$, and find the vector(s), if any, that are mapped to $\overrightarrow{\mathbf{w}}$.
$T(x, y)=(x+y, x), \quad \overrightarrow{\mathbf{u}}=(1,0), \quad \overrightarrow{\mathbf{w}}=(3,1)$