In order to write a balanced equation, all you have to do is look at your atoms on each side and make sure there are the same amount present on either side.
K 1 | K 1 OH 1 | OH 3 Al 1 | Al 1 NO3 3 | NO3 1
So what you would need to do is add a coefficient in front of each compound to make sure there is the same amounts on either side. Your equation should look like this at the end: