You could rage and produce no results or you could just raise your power. This is what I did after trying out the many guides out their in the forum and on youtube and it didn't work out for me. So I just raised my power and kept on trying until I was able to beat it. Remember, certain classes will be easier to do certain ninja exams so you could switch mains. There is a reason why it is much easy to do ninja exam 140 as an earth main compared to any other main.