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)
Answer:
16xpi
Step-by-step explanation:
To find the area of a circle the formula is pi r squared.
r represents radius, aka 4x.
4 times 4 yields 16.
Leaving you with 16xpi
Thus should be fun I know I might do
960 watts = 24 hours
4 days = 96 hours
960 (watts) x 4 (days) = 3840 watts
12 hours= 480 watts
6 hours = 240 watts
18 hours = 720 watts
3840 (4 days) + 720 (18 hrs) = 4560