Answer:

Step-by-step explanation:
Let points D, E and F have coordinates
and 
1. Midpoint M of segment DF has coordinates

2. Midpoint N of segment EF has coordinates

3. By the triangle midline theorem, midline MN is parallel to the side DE of the triangle DEF, then points M and N are endpoints of the midsegment for DEF that is parallel to DE.
You see how these 2 angles marked are both inside the 2 parallel lines?
And they are on opposite side of the transversal, the line crossing the 2 parallel lines?
These 2 angles are alternate interior angles and they are equal, I think you can do the last part by yourself.
8 . You round 31.9 to 32 then divide it by 4 which gives you 8
16.64 average of the four races that kerri ran in seconds.