#### Answer

(a) $(4, 10)$
(b) $(3, -2)$

#### Work Step by Step

Recall:
The midpoint of the points $P(x_1, y_1)$ and $Q(x_2, y_2)$ is $\left(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}\right)$.
Use the formula above to find the midpoint of each ordered pair:
(a) $\text{midpoint} = \left(\frac{3+5}{2}, \frac{7+13}{2}\right)=(4, 10)$
(b) $\text{midpoint} = \left(\frac{-2+8}{2}, \frac{3+(-7)}{2}\right)=(3, -2)$