It would take greater than 31.25 hours for Tim's price to be better. So in terms of whole hours it would take at least 32 hours of work for Tim's price to be better.
If B is the midpoint of AC, that means that the distances from A to B and B to C are the same. The distance from A to B is 8x + 4, and the distance from B to C is 10x - 6, so we can set these two equivalent:
8x + 4 = 10x - 6
Solving for x:
4 = 2x - 6 (subtract 8x from both sides)
10 = 2x (add 6 to both sides)
5 = x (divide both sides by 2)
So, x = 5, which is the second option given.
5 kilometers = 5000 decimeters if that answers your question sorry ...
+ √6 = √9
The first step is to get by itself. We can do this by subtracting 
from each side, and simplifying 
= 3 -
Now we square both sides
5x = (3 - )²
Using the formula (a - b)² = a² -2ab + b², (3 - )² = 15 - 6
5x = 15 - 6
x = 
