I'm assuming you are solving for "z". its simple algebra to get what "z" is you have to get "z" by itself to do that you would subtract 4 from each side z+4=9 -4 -4 z = 5
you want to get the variable alone so you subtract 4 from both sides canceling out the 4. subtract 4 from 9 then you should get 5, after you divide the variable by 5. the answer is z=5
