A net yardage of -26(1/3) yards would mean that the ball is twenty six and a third yards behind where the team started the first down. So first, the ball would have to travel the 26(1/3) yards to the original line of scrimmage plus another 10 yards to get the first down.
26(1/3) + 10 = 36(1/3) yards.
Another way to calculate distance traveled is Distance = End Position - Beginning Position
Therefore, Distance = 10 - (-26(1/3)) = 36(1/3) yards.
Either way, same answer.
