15-k. K=Kelsy.
9d. D=doughnuts purchased
23+e. E=elaina's earnings
Answer: 
Step-by-step explanation:
The perimeter of a rectangle can be calcualated with this formula:

Where "l" is the lenght and "h" is the height.
The area of a rectangle can be found with this formula:

Where "l" is the lenght and "h" is the height.
In this case we know that:

Therfore, we can susbsitute them into
and solve for "h" in order to find its value:

Find two number whose sum is 3 and whose product is -40. These are -5 and 8. Then, factorizing, we get:

The positive value is the height. Then:

Since the length is 3 centimeters greater than its height, we get that this is: Then:

Substituting values into
, we get that the perimeter is:

21x - 19 = 3x + 17 |add 19 to both sides
21x = 3x + 36 |substract 3x from both sides
18x = 36 |divide both sides by 18
x = 2
Each step subtracts 3 from the previous number.
14 - 3 = 11
11 - 3 = 8
The sequence will continue:
8 - 3 = 5
5 - 3 = 2
2 - 3 = -1
Etc.
14, 11, 8, 5, 2, -1...
<h3>
Answer: Choice C) x^4 - 2</h3>
Explanation:
If the exponent is negative, then that means we apply the reciprocal. So something like x^(-2) becomes 1/(x^2). A polynomial cannot have a variable in the denominator like this. So we can rule out choices A, B, and D. Choice C is the only thing left. It is a polynomial because the exponent is a positive whole number.