Answer:
I think it's the last to they sound way more independent!!!
The total amount of calories burnt in jogging 2 miles = 185 calories
We have to determine the number of calories burned in jogging 3 miles.
Firstly, we will determine the amount of calories burnt in jogging 1 mile. We will use unitary method to evaluate this.
So, the total amount of calories burnt in jogging 1 mile = 
= 92.5 calories
So, the amount of calories burnt in 3 miles = 
= 277.5 calories
Therefore, 277.5 calories are burned in jogging 3 miles.
Pairs, in this case, relates to a group of 2 or more. We have 6 friends. Let's call them A,B,C,D,E,F. This will allow us to make a [some sort of] combination tree:
1. ABC against DEF
2. ABD against CEF
3. ABE against CDF
4. ABF against CDE
5. ACD against BFE
6. ACE against BDF
7. ACF against BDE
8. ADE against BCF
9. ADF against BCE
10. AEF against BCD
I believe there are 12 combinations... I just can't think of the last 2 though.
Hypotenuse or C (x) can be found with the equation

After solving you get about 6.32
6.32 about the same as