Answer
a) $\dfrac{-2}{3}$
b) A slope of $\frac{-2}{3}$ means that if $x$ increases by $3$ units, then $y$ decreases by $2$ units.
Work Step by Step
The slope $m$ of the line that contains the points $P_1(x_1,y_1)$ and $P_2(x_2,y_2)$ is given by the formula
$m=\dfrac{y_2-y_1}{x_2-x_1}$
a) Hence, the slope of the line that contains the two given points is
$m=\dfrac{-1-3}{5-(-1)}=\dfrac{-4}{6}=\dfrac{-2}{3}$
b) This means that if $x$ increases by $3$ units, then $y$ decreases by $2$ units.
