To find midpoint between points $ A(x_1,y_1) $ and $ B(x_2,y_2) $, we use formula:

$$ M = \left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right) $$

In this example we have:

$$ \begin{aligned} & A \left(1,~-7\right) \implies x_1 = 1 ~~\text{and}~~ y_1 = -7 \\[1 em] & B \left(1,~-12\right) \implies x_2 = 1 ~~\text{and}~~ y_2 = -12 \end{aligned} $$

After substituting into above formula, we get:

$$ \begin{aligned} M & \left( \frac{ 1 + 1 }{2}, \frac{ -7 + \left( -12\right) }{2} \right) \\[1 em] M & \left( \frac{ 2 }{2}, \frac{ -19 }{2} \right) \\[1 em] M & \left(1,~-\dfrac{ 19 }{ 2 }\right) \end{aligned} $$

Midpoint Calculator