To solve the equation 2.4x - 1.2x = 15, we first isolate the variable term by subtracting 1.2x from both sides. This gives us 2.4x - 1.2x = 15, which simplifies to 1.2x = 15. Next, we divide both sides by 1.2 to solve for x. This results in x = 15 / 1.2, which simplifies to x = 12.5. Thus, the solution to the equation is x = 12.5.