How do you balance

Al(OH)3 --> Al2O3 + H2O

Why does the OH decompose into O3 and H2O??

This equation is not that hard to balance. It is done by trial and error. AND to set things straight, OH deos not decompose to O3. It is correct to say that Al(OH)3 decomposes to Al2O3 and H2O.Where do you have trouble balancing it. My first trial would be a coefficient of 2 for Al2O3.