If the Eagles start with 48 yards left then gain 31, you would subtract 31 from 48. So 48-31=17. So they had 17 yards to go. On the next four plays the lose yards, so add up all the yards lost in those four plays. 3+5+7+4 which equals 19. So they were 17 yards away but then they lost 19 yards so you would add 17 and 19, which gives you 36. So therefore the ball is 36 yards away from the goal line after those five plays.
