Question Id: 2013025 Solve the following equation for \( x \). \[ a x-3=18 \] A \( \quad x=21-a \) B \( \quad x=\frac{21}{a} \) C \( \quad x=\frac{a}{21} \) D \( \quad x=\frac{15}{a} \)

To solve the equation \( a x - 3 = 18 \), we first add 3 to both sides: \[ a x = 18 + 3 \] \[ a x = 21 \] Next, we divide both sides by \( a \): \[ x = \frac{21}{a} \] So the correct answer is **B \( x=\frac{21}{a} \)**. Now, let's consider some engaging background information: The concept of solving linear equations has been around for thousands of years! Ancient civilizations, including the Babylonians and Egyptians, were already tackling algebraic problems without formal notation. They’d use geometric methods and verbal expressions, often leading to surprisingly accurate solutions for problems we can now write as simple equations. If you enjoy solving equations, you might want to explore how algebra is applied in various professional fields. Engineers, for example, rely on algebra to optimize design structures or to analyze forces within mechanical systems. It's fascinating how these mathematical principles govern everything from building skyscrapers to launching rockets!