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Evaluating expressions involves calculating the value of a given mathematical statement. In our exercise, we aim to evaluate the expression \(|20-12|\). This requires performing operations inside the absolute value first and then applying the absolute value operation.

To start, always do the operations inside parentheses or absolute value first. For our expression, we need to evaluate the difference between 20 and 12. This is a crucial step because it simplifies the expression before applying any other operations.

Once the internal calculation is completed, the next step is to consider the absolute value, which converts a result into its non-negative counterpart. Thus, evaluating an expression with absolute values often involves two stages: internal operations and conversion to a positive result.

Let's move on to more specific steps like subtraction and understanding elementary algebra.

Subtraction is one of the four fundamental arithmetic operations. In this exercise, we need to subtract 12 from 20.

To break it down:

• 20 is our minuend (the number from which we subtract).
• 12 is our subtrahend (the number we subtract).
• The difference is the result of our subtraction operation.

Calculating this gives us: \[ 20 - 12 = 8 \]

This difference (8) is now inside the absolute value symbols. It is essential to understand subtraction clearly as it is the basis of many more complex mathematical operations. Practicing basic subtraction improves overall math skills and prepares you for more advanced topics.

Elementary algebra introduces the use of variables and the fundamental operations to construct and solve simple equations.

The absolute value operation, indicated by the bars \(|...|\), is part of elementary algebra.

• The absolute value of a number is its distance from zero on the number line, regardless of direction.
• This means \( |x| \) equals \ x \ if \( x \) is positive or zero, and \(-x\) if \ x \ is negative.

For our example, \(|8|\), since 8 is positive, the absolute value remains 8.

Elementary algebra helps in understanding how to manipulate abstract symbols and solving equations by applying standard operations, such as:

• Addition
• Subtraction
• Multiplication
• Division

Mastering these basics is critical for progressing in more complex mathematics and grasping advanced algebraic concepts.