Can someone please help me with this

The answer is (9,11) 

Midpoint formula: (x1 + x2)/2, (y1 + y2)/2, where (x1, y1) and (x2, y2) are the endpoints of the segment 

x-coordinate of midpoint = (x1 + x2)/2 
5 = (1 + x2)/2 
10 = 1 + x2 
9 = x2 

y-coordinate of midpoint = (y1 + y2)/2 
3 = (-5 + y2)/2 
6 = -5 + y2 
11 = y2