To solve for x we need to isolate it by subtracting 5 from both sides of the equation. We want to subtract 5 because addition and subtraction are inverse operations - they cancel each other out. This is allowed by the Subtraction Property of Equality.
An identity occurs when the left-hand side and the right-hand side of an equation are equal to one another. Since substituting x=-3 resulted in an identity, our solution is correct.
