This question is quite easy. During my last revision which is few months ago, I manage to get the same answer as my teacher ( the answer is written in my book behind the question paper) But today I am doing revision again for my maths exam next week, I am doing the same question but I can't get the answer correct. What I mean by correct is same answer as my teacher. Here it is, please solve this EDIT: SOLVED THANKS EDIT: SOLVED THANKS Do this question if you want =D