Ans: Let it started from zero. And it lasts 6 yards means that -6 represents a loss of 6 yards.
After that, the team lost 5 yards. So, -11 will represent a loss of 5 yards
The team after gaining 12 yards on next day will not be at their starting position. Instead, it will be at ‘1yard’ more than the starting position. The number will be ‘1’ which will represent the position of the team after gaining 12 yards.