Answer:
Let's use these two sets given to explain what is the domain.
Each value from the left set is x, and from the right is f(x).
If we plug any x from the left set in the function, we'll get f(x) that corresponds to it and that's exactly what the arrows are showing.
Domain of the function is, basically, a set of all values x can have.
In this case, it's easy to see, those are all members of the left set (-6, 1, 5, 8), but sometimes this set can have lots and lots of members, even infinity.
Answer:
1. 
2. 
3. The first one represents Dale's commission
Explanation:
1. The composition of the function
means that you first apply the function g(x) and then f(x) on the output of g(x).
That is:
- f(x) = 0.05x
- g(x) = x - 3000


2. The composition of the function
means that you first apply the function f(x) and then g(x) on the output of f(x).
That is:

3. Which one represents Dale's commission
To calculate Dales's commision you must subtract $3,000 from the sales, to find the sales over $3000. That is: x - 3,000, which is the function g(x).
Therefore, you first use g(x).
Then, you must multiply the output of g(x) by 0.05 to find the 5% of the sales over $3,000. That is: 0.05(g((x)) = 0.05(x - 3000) = 0.05x - 150.
Therefore, the composition that represents Dale's commission is the first one:


Have two sets of parallel sides
2x + x = 54 wher x = number of girls
3x = 54
x = 18
18 girls