Answer :
252 plus 178 plus 120 =550 but if you have estimated right 252 is close to 300 and 178 is close to 200 and 120 is close to 100 if you have added them up you would have gotten 600 feet so what you did wrong was you underestimate you did 200 plus 100 plus 100 and you originally got 400 the correct answer was 600 total feet