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Negative numbers are numbers that are less than zero. They are usually written with a minus sign in front of them, like \(-3\) or \(-9\). Understanding how to work with negative numbers is very important in algebra and everyday math.
When you add two negative numbers, think of moving left on a number line. For example, if you start at \(-9\) and move left by 3 more units, you end up at \(-12\).
Here are some important points to remember:

• Adding a negative number is like subtracting a positive number.
• Subtracting a negative number is like adding a positive number.
• The sum of a negative and a positive number is found by subtracting the smaller absolute value from the larger absolute value, then attaching the sign of the number with the larger absolute value.

The order of operations is a set of rules that tells you the correct sequence to evaluate a math expression. You can remember it by the acronym PEMDAS, which stands for:

• P - Parentheses (or brackets)
• E - Exponents (or powers)
• M - Multiplication
• D - Division
• A - Addition
• S - Subtraction

In the exercise \([(-9)+(-3)]+12\), we follow the PEMDAS rule. First, we solve the expression inside the brackets \((-9) + (-3)\). This results in \(-12\).
Next, according to the order of operations, we add this result to 12, which gives us the final answer, 0.
Remembering to always follow the order of operations helps you get the correct answer.

Brackets, also known as parentheses, are used in math to group parts of an equation together. This tells you to solve the expression inside the brackets first before doing any other operations.
In the problem \([(-9)+(-3)]+12\), the numbers \(-9\) and \(-3\) are inside the brackets. This means we need to first add these two negative numbers together, giving us \(-12\).
Only after solving the bracketed expression do we proceed to the next step in the equation.
Brackets make sure that the math is done in the correct order, as suggested by the order of operations. Besides parentheses \( ( ) \), there are other types of brackets like square brackets \( [ ] \) and curly braces \( \{ \} \), each serving the same purpose of grouping expressions.