You should now have ax alone on one side of the equation, right? So you want to get x by itself, then you will be finished. Do the same thing to both sides of the equation: divide by ????

(DO NOT CLICK ON THAT, you do not need any more help.)

If equations like this seem impossible to you, get help from some friendly, mathematically literate person. If you cannot solve these simple equations, forget physics for now. Go into rock & roll or law or something.

Better yet, do another problem