Your question seems incomplete :-(
To get the coordinates, we would use the midpoint formula (google it)
(X1-X2/2 , Y1+Y2/2)
(-3+0/2 , -1+1/2)
N: (-3/2,0)
The 2 smallest lengths in a triangle have to add up to be greater that the longest side of the triangle. In this case, the longest side is 20. The 2 smallest sides are 5 and 10. 5+10=15, but 15<20. This is why these 3 lengths can’t create a triangle.
B. 12 would be your answer
