Answer:
Graph 1: Y is not a set number Graph 2: Y is 5
Step-by-step explanation:
Answer:
a. The critcal points are at

b. Then,
is a maximum and
is a minimum
c. The absolute minimum is at
and the absolute maximum is at 
Step-by-step explanation:
(a)
Remember that you need to find the points where

Therefore you have to solve this equation.

From that equation you can factor out
and you would get

And from that you would have
, so
.
And you would also have
.
You can factor that equation as 
Therefore
.
So the critcal points are at

b.
Remember that a function has a maximum at a critical point if the second derivative at that point is negative. Since

Then,
is a maximum and
is a minimum
c.
The absolute minimum is at
and the absolute maximum is at 
Well, you could assign a letter to each piece of luggage like so...
A, B, C, D, E, F, G
What you could then do is set it against a table (a configuration table to be precise) with the same letters, and repeat the process again. If the order of these pieces of luggage also has to be taken into account, you'll end up with more configurations.
My answer and workings are below...
35 arrangements without order taken into consideration, because there are 35 ways in which to select 3 objects from the 7 objects.
210 arrangements (35 x 6) when order is taken into consideration.
*There are 6 ways to configure 3 letters.
Alternative way to solve the problem...
Produce Pascal's triangle. If you want to know how many ways in which you can choose 3 objects from 7, select (7 3) in Pascal's triangle which is equal to 35. Now, there are 6 ways in which to configure 3 objects if you are concerned about order.
6x + 18y = 18. Let us take x = 0
6(0) + 18y = 18
0 + 18y = 18
18y = 18
y = 18/18
y = 1
(0, 1) [x = 0, y = 1]
6x + 18y = 18. Let us take y = 0
6x + 18(0) = 18
6x + 0 = 18
6x = 18
x = 18/6
x = 3
(3, 0) [x = 3, y =0]
Infinite solutions can be found for x and y
X + x + 1 + x + 2 + x + 3 = 330
4x + 6 = 330
4x = 324, x = 81
Smallest number: 81
Biggest number: 81 + 3 = 84
Sum: 81 + 84 = 165
The answer is 165