Answer:

Subtract 9 from both sides:


Multiply both sides by 2:


No, -4 is not a natural number. It is a negative, the only natural numbers are positiv numbers. Hope this helped!
Answer:
<h3>-90</h3>
Step-by-step explanation:
To use the order of operations stands for (Parenthesis, Exponents, Multiply, Divide, Add, and Subtract) left to right.
Please Excuse My Dear Aunt Sally!
BOMDAS- (Brackets, Of, Multiply, Divide, Add, and Subtract) from left to right.
First, do parenthesis.
(3-21)=-18
-18(3+2)
Add.
3+2=5
-18*5
Multiply.
-18*5=-90
-90
So, the final answer is -90.