Answer
$$\text{slope}=0$$
Work Step by Step
RECALL:
The slope $m$ of the line that contains the points $(x_1, y_1)$ and $(x_2, y_2)$ can be found using the formula:
$$m=\dfrac{y_2-y_1}{x_2-x_1}$$
Use the formula above to obtain:
$$m=\dfrac{-7-(-7)}{3-0}
\\m=\dfrac{0}{3}
\\m=0$$