AL(OH)3 + NaOH= NaAlO2 + H2O

write it out like this

H + O --> H2O

now write out the element seperatly going under the equation
H + O --> H O
________ H

now to balance it

H + O --> H O
H _______ H

so you can see you need two Hs on the left hand side to match the two Hs on the other side

2H + O --> H2O

------------

Now for yours

Al (OH)3 + NaOH --> NaAlO2 +H20

Al OH + NaOH --> NaAlO + H 0
__OH______________O ___ H
__OH

So you have on the left side
4 Os
4 Hs

And on the right
3 Os
2 Hs

So what can you do to get another O and two more Hs?

nb sorry about the __ only way I could get stuff to line up

I'm assuming you would like this solved ^_^

This is really easy, but what's hard is comprehending what you are needing to do. Everything on one side needs to be on the other. Right now, you know that these chemicals put together, make those two chemicals through a chemical process. What you don't know is how many molocules it takes to make this reaction happen. The left side must equal the right side. If it has parenthesis, you must multiply the number in script. If there isn't a plus next to it, it has to be multiplied with the entire molecule. (ie AL(OH)3 ) So, if you put the coefficient 2 in front of H20 (2[H20]) You'll have balanced out the equation. Its hard for me to go into detail, as its been forever since I used the lingo. If you are still confused about the comprehension, just ask ^_^ I'll try to help