Step-by-step explanation:
use the midpoint formula
[tex]( \frac{x1 + x2}{2} \: \: \frac{y1 + y2}{2} )[/tex]
substitute into substitute midpoint formula
[tex]( \frac{ - 1 + 7}{2} \: \: \frac{5 + ( - 5)}{2} )[/tex]
solve the above
[tex](3 \: \: 0)[/tex]
answer is
(3;0)