Precalculus (6th Edition) Blitzer

$3u+4v=-6i+13j$
We are given that the two vector equations for the vectors $v$ and $v$ as follows: $v=-3i+7j$ and $u=2i-5j$ Now, $3u+4v=3(2i-5j)+4(-3i+7j)=(6-12)i+(-15+28)j$ Hence, $3u+4v=-6i+13j$