15-x=3

To solve the equation \( 15 - x = 3 \), follow these steps:

1. Subtract 15 from both sides of the equation: \[ -x = 3 - 15 \] \[ -x = -12 \]

2. Multiply both sides by -1 to solve for \( x \): \[ x = 12 \]

So, the solution is \( x = 12 \).