How algebra lets us describe what we don't yet know
A variable is a symbol that represents a quantity we don't know yet — or a quantity that can change. When you write x + 5 = 12, you're not just writing math. You're asking a question: what number, when 5 is added to it, equals 12? Algebra is the art of posing and answering precise questions about unknown quantities. Every engineer, scientist, economist, and programmer uses this daily.