91Ó°ÊÓ

Arithmetic is the branch of mathematics dealing with numbers and their operations. In this problem, we are performing subtraction with negative numbers. The key to solving this is understanding how negative numbers work.
When we subtract or add negative numbers, we often need to think in terms of combining or removing values.
For example, subtracting a positive number from a negative number makes it more negative.
Combining negative numbers involves adding their absolute values and assigning a negative sign to the result. In this case, combining \(-5\) and \(-4\) means finding the absolute values of 5 and 4, adding them to get 9, and then applying the negative sign to get \(-9\).

Simplification involves making an expression as simple as possible. This often means combining like terms and performing basic arithmetic.
In our exercise, \(-5 - 4\), simplifying means recognizing both numbers as negative and combining them.
First, ignore the negative signs and add the absolute values: 5 and 4, which equals 9.
Since both original numbers were negative, we put a negative sign in front of 9 to get \(-9\). That is the simplest form of the expression.
Simplification helps in making calculations easier and more understandable.

Absolute value refers to the distance of a number from zero on the number line, without considering which direction from zero the number lies.
It is always a non-negative number. For example, the absolute value of \(-5\) is 5, and the absolute value of 4 is 4.
In our simplification problem, understanding absolute value is crucial.
We take the absolute values of \(-5\) and \(-4\)—which are 5 and 4, respectively—before combining them during the arithmetic operation.
After combining, we reapply the negative sign to the result because both original numbers were negative. This results in \(-9\).