All you have to do for this is follow the midpoint formula.
Let me know if the picture is unclear and I'll type it out for you.
The correct answer is 0.1
Step-by-step explanation:
(b) If
then
Note that
cancel out so we get

Solving for
we get

(c) I'm not sure what the problem is asking for but here goes. As r doubles,
becomes

Answer:
12 of them
Step-by-step explanation:
2:4
4:8
6:12