Adding and subtracting big polynomials like these are pretty easy. You just need to combine like terms. For example:
1.)

2.)


(The 3x^2 and the 2 stay intact while the 5xy and 7xy combine together)
All you have to do is combine the numbers that have the same powers of x and y with each other. x^2 will combine with x^2 and xy^2 wil combine with xy^2 exc. If there is no other number with the same x and y's, then you just leave it as it is in the answer.
Now with the original question, I see a -9xy^3, and thats gonna combine with the 3xy^3 in the second polynomial and the 2xy^3 in the third one.

So far we have -4xy^3, the next term is going to be a -9x^4y^3, and that's gonna combine with the 3x^4y^3 in the third one.

We now finished adding the like terms that were in the first polynomial, we will move onto the second polynomial. The first term in this one is 3xy^3, in which we already added in the first step. At this point, it doesn't look like there are any other terms that have the same x and y behind them. So we can move on and write the final answer:

(All on the same line of course)
Also, for your second question, the order does not matter in which you write the terms. I could write the 7y^4 behind the -8x^4y^4 and it would still be the same answer.
If you have any other questions let me know :) while I double check my work.
Answer:
Input variable x: Number of classes he attends.
Output variable y: Monthly cost
Slope: Cost per class, of $2
y-intercept: Membership fee, of $25.
Function: 
Step-by-step explanation:
This situation can be represented by a function is the following format:

In which y is the monthly cost(output), m is the cost per class(slope), x is the number of classes he attends(input) and b is the membership fee(y-intercept).
We have that:
There is a membership fee of $25 per month and a fee of $2 per workout class he attends.
This means that
. So

Answer:
For a bilateral test the p value would be:
Step-by-step explanation:
Information given
n=225 represent the sample selected
X=87 represent the households with incomes below the poverty level
estimated proportion of households with incomes below the poverty level
is the value that we want to test
z would represent the statistic
represent the p value
System of hypothesis
We want to check if the true proportion is equal to 0.32 or not.:
Null hypothesis:
Alternative hypothesis:
The statistic is given bY:
(1)
Replacing we got:
For a bilateral test the p value would be:
Answer:
the number of miles is 160
Step-by-step explanation:
The computation is given below:
Let us assume the miles be x
For company A
y = $100 + $0.40x
And, for company B
y = $20 + $0.90x
In order to find out the number of miles, the rental cost of the company A should be less than the company B rental cost
SO,
$20 + $0.90x > $100 + $0.40x
Subtract $20 from both sides
0.90x > 80 + 0.40x
Now subtract 0.40x from both sides
0.50x >80
x>160
So the number of miles is 160
Given:
land area of Alaska: 1,700,000 square kilometers
land area of Florida: 0.10 of Alaska
To find the land area of Florida, we multiply its decimal to the land area of Alaska
1,700,000 sq. km * 0.10 = 170,000 square kilometers.
The land area of Florida is 170,000 square kilometers. It is equal to 0.10 or 10% of the land area of Alaska.<span />