The answer is 256.25
EXPLANATION
Let
represent the number.
Then, 
We cross multiply yo obtain,

We now divide both sides by 16.

This will give us,

Therefore the number is 256.26
Answer:
(-4,-1) is the answer unless your asking for an actual equation
There are seven (7) friends.
The first friend to board can be any one of the 7. For each of them ...
The 2nd one to board can be any one of the remaining 6. For each of them ...
The 3rd one to board can be any one of the remaining 5. For each of them ...
The 4th one to board can be any one of the remaining 4. For each of them ...
The 5th one to board can be any one of the remaining 3. For each of them ...
The 6th one to board can be either of the remaining 2. For each of them ...
The 7th one to board is the last 1 standing.
The number of different ways that this could play out is
(7 x 6 x 5 x 4 x 3 x 2 x 1) = <em>5,040</em>