$$\color{rgb(255,0,0)}\vec{u}$$

$$\color{rgb(255,0,0)}\vec{u}\left( \begin{array}{l} {4 } \\ {- 3 } \end{array} \right)$$

$$\color{rgb(255,0,255)}\Delta_y = - 3$$

$$\color{rgb(0,0,255)}\Delta_x=4$$