Answer:
Step-by-step explanation:

From the initial condition,

So we have that 
Perform indicated multiplication:
11c+3(-5c)+3(4d)
11c-15c+12d combine like terms
(11c-15c)+12d
-4c+12d factor
4(3d-c)
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)