You have a lot of questions here, I can help you with a few of them.
When you simplify the polynomials, you put together all of the terms that have the same degree. That means the variables have the same exponents. The number of terms are the items separated by plus and minus signs.
Here are the answers for the first three:
1)

2)

3)
If y varies directly with x, means that they can be modeled by a linear equation, lets choose a line with 0 y intercept, that is:
y = mx + b
y = mx
where m is the slope of the line, now we plug in the data we have:
y = mx
20/3 = m(30)
solving for m:
m = (20/3)(1/30)
m = 20/90
m = 2/9
so the line equation, or function modeling the y and x relationship is:
y = (2/9)x
Add them all around the top pointing down
Answer: D
Explanation: to find whether two instances are proportional, find the rate of change for each situation. Simply divide both numbers from both situations and if the numbers are not the same they are not proportional.
Answer:
Step-by-step explanation:
Check attachment for solution