Chapter 13 - Vector Geometry - 13.1 Vectors in the Plane - Exercises - Page 650: 50

$$\mathbf{v}= \langle 2,-1\rangle $$

$$ 3 \mathbf{v}+\langle 5,20\rangle=\langle 11,17\rangle \Longrightarrow 3 \mathbf{v}=\langle 11- 5,17-20\rangle\\ \Longrightarrow \mathbf{v}=\frac{1}{3}\langle 6,-3\rangle=\langle 2,-1\rangle $$