Hello!
You solve this algebraically
4n - 9 = -9
Add 9 to both sides
4n = 0
Divide both sides by 4
n = 0
The answer is 0
Hope this helps!
There are some online calculators
Step-by-step explanation:

Answer:
but where is the polygon....?????
I hope this helps you
if per pound is $25
how much cost ?
C=25/pounds