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Understanding the four basic arithmetic operations—addition, subtraction, multiplication, and division—is essential for grasping higher mathematical concepts.

Subtraction, one of these core operations, typically involves taking one number away from another. For instance, if you have 5 apples and you give away 2, you subtract 2 from 5, which leaves you with 3 apples. This is written mathematically as \( 5 - 2 = 3 \).

However, when negative numbers enter the mix, the rules adjust slightly to accommodate them. The introduction of negative numbers is often the first step towards understanding more complex mathematical ideas, and it requires a solid grasp of how basic operations function when negative values are involved.

Adding negative numbers can sometimes appear counterintuitive, but with a simple change in perspective, it becomes as straightforward as basic addition.

Think of negative numbers like debt. If you 'subtract' a debt, you're effectively removing a negative, which is the same as gaining a positive. So, subtracting a negative number can be rephrased as adding its positive counterpart.

For instance, in the given exercise \(7 - (-2)\), instead of taking away a negative, you are adding a positive, so it becomes \(7 + 2 = 9\). This 'rule of signs' is a fundamental aspect of dealing with negative numbers and serves as a stepping stone towards mastering arithmetic operations involving negatives.

Algebraic expressions are a cornerstone of algebra and represent a combination of variables, numbers, and arithmetic operations.

The expression from the exercise, \(7 - (-2)\), though simple, is an algebraic expression as it includes numbers and an operation. It is a specific example of how algebra manipulates numerical and symbolic elements to display and solve problems.

In primary algebra, you'll learn to simplify expressions by combining like terms and using arithmetic laws, including those governing the handling of negative numbers. As algebraic complexity increases, so does the need for a solid foundation in how basic operations work in various contexts.