Answer:
The slope of midsegment which is parallel to AC is -4.
Explanation:
We know that the slopes of parallel lines are same. It is given that the midsegment is parallel to AC, therefore the slope of AC and slope of midsegment is equal.
The slope of a line is

From the given figure it is noticed that A(3,7) and C(5,-1).
Slope of AC is

Since the midsegment is parallel to AC, therefore their slopes are equal.

Therefore the slope of midsegment which is parallel to AC is -4.