Answer
$slope=2$
Work Step by Step
To calculate the slope between points $(x_1,y_1)$ and $(x_2,y_2)$, we use the formula:
$slope=m=\frac{y_2-y_1}{x_2-x_1}$
We see that the two blue points on the line are: $(1,-1)$ and $(3,3)$. We plug in the points into the slope equation:
$slope=m=\frac{y_2-y_1}{x_2-x_1}=\displaystyle \frac{3-(-1)}{3-1}=\frac{4}{2}=2$
