According to the associative property of equality: (a + b) + c = a + (b + c) we can see that the parenthesis do not mean anything when we are only doing addition.
So answers 1. and 3. are correct.
<em>Thanks Associative Property!</em>
Answer:

Step-by-step explanation:


Used PEMDAS:
P Parentheses first
E Exponents (ie Powers and Square Roots, etc.)
MD Multiplication and Division (left-to-right)
AS Addition and Subtraction (left-to-right)
First Power, next Addition
B..............
c>=3 and n<0 and p<=(9-3 c)/n