It helps to do them one at a time. start with Aluminum and see if there is one on the other side. There is, so that one's done now move on to NO3. there are three of them on the left but only one on the right so you need to add a three b on the right side. continue this process until you see there are an even number of molecules on both sides.
Al(NO₃)₃ + 3NaOH → Al(OH)₃ + 3NaNO₃
