Answer:
Coordinates of midpoint are (8,1.5).
Explanation:
Given coordinates of end points are;
(7,4) and (9,-1) 
we can find the coordinates of mid-point, 

Here, 
x1 = 7 and y1 = 4 
x2 = 9 and y2 = -1 
Putting these values in formula 
Coordinates of mid point = 

Midpoint = 

Midpoint = 

Midpoint = 8 , 1.5
Hence, 
Coordinates of midpoint are (8,1.5).