CB-MA006-261013: Subtracting Negative Numbers

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You also need to be able to subtract negative numbers comfortably. If you consider negative numbers as "debts", then you remove a debt when you subtract a negative number. Removing a debt of 4 dollars is like being given 4 dollars. This explains why the equation $$5-(-4)=5+4$$ holds: subtracting negative four is the same as adding positive four.

The symbols $$-(-4)$$ also represent "the additive inverse OF (the additive inverse of $$4$$)". Our work with additive inverses can help you write this expression in a different and simpler way. After all, the additive inverse of $$4$$ is $$-4$$, and now the additive inverse of $$-4$$ is, by definition, a number that results in zero when added to $$-4$$. Of course, the additive inverse of $$-4$$ is $$4$$ itself. All of this tells us that $$-(-4)=4$$. In the next section, we will discuss multiplying and dividing negative numbers.

Source: Algebra2Go,

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