There are 5280 feet in a mile:
5280ft/mi
When using proportions to solve for unknown quantities, you need to keep the same units on the same side. This means keep "ft" on the top side and "mi" on the bottom side.
I would go with the second choice.
Answer: 504
Step-by-step explanation:
When we select r things from n things in a order , we use permutations.
Formula for permutation: 
Given : The number of family members who are potential kidney donors. = 9
Number of people needed to be selected for best match, a second-best match, and a third-best match ( in an order)=3
Then, the number of possible orders are = 

Hence, the number of possible orders 504.
The original value was <span>£720.
720 x .15 (15%) = 108
720 + 108 = 828 </span>