81. A straight line intersects the $O x$ axis at some point $M$ and passes through points $A(-2 ; 5)$ and $B(3 ;-3)$. Find the coordinates of point $M$.
Solution. Points $A(-2 ; 5), B(3 ;-3), M(x ; 0)$ lie on the same line, hence condition $(8)$ must be satisfied:

$$
\frac{0-5}{-3-5}=\frac{x-(-2)}{3-(-2)} \text { or } \frac{5}{8}=\frac{x+2}{5} \text {, }
$$

from which $x=1 \frac{1}{8}$. Point $M\left(\frac{9}{8} ; 0\right)$ is the desired one.