Answer:
(29,-13)
Explanation:
You can tackle this for x and y coordinate separately.
For x, the line starts at -9 and is halfway at 10. The distance between -9 and 10 is 19 so it has another 19 to go, which puts the endpoint at 10+19=29.
Same for y: from 7 to -3 is 10 down, another 10 to go, puts you at -13.
Formula: x,y of midpoint is ((x1+x2)/2, (y1+y2)/2)