Answer:
KM = 20
Step-by-step explanation:
If V is the midpoint of KM, then ...
KV = VM
2.5z = 5z -10
0 = 2.5z -10 . . . . . . subtract 2.5z
0 = z - 4 . . . . . . . . . divide by 2.5
4 = z . . . . . . . . . . . . add 4
We know that V bisects KM, so KV is half the overall length. That is ...
KM = 2·KV = 2·2.5z = 5z
Using the value of z we found, ...
KM = 5·4 = 20
