x=6
Step-by-step:
1. Combine like terms: 3x-x=2x
2. Rewrite equation: 2x-3=9
3. Add 3 to both sides of the equation to isolate the variable: 2x-3+3=9+3
4. Rewrite equation: 2x=12
5. Divide both sides of equation by 2 to further isolate x: 2x/2=12/2
6. Rewrite equation: x=6
