Answer:
First is correct
Second is perimeter
Why? Because perimeter is the surounding part
Answer:
The value of 
Step-by-step explanation:
Being the general expression of the sequence:

We replace the value n=12 to get

4≤x/2.1
To Solve
Multiply by 2.1
8.4≤x
Answer:
I only know the first one....
4+2+1=7
49p/7= 7p
4units:2units:1units
4×7p= 28p
2×7p= 14p
1×7p= 7p
divided it is...
28p:14p:7p