Answer:
507
Step-by-step explanation:
As they said, I will be using 3 as pi.
(pi)
(radius squared)
Without annotations: 

; 


Step-by-step explanation:
D. Both charges must be different.
Because, like charges repel each other and different charges attract each other.
Answer:

Step-by-step explanation:
Write down the problem;

Simplify

Convert so that the fractions have a common denominator; multiply the numerator and denominator of both fractions such that the denominators are equal;

Add the fractions;

Convert to mixed number;

Answer:
18:162
Step-by-step explanation:
1:9
1+9=10
(1×180)÷10= 18
(9×180)÷10=162