The farthest arrow shot using the feet is 12.31 m (40 ft 4.64 in) and was achieved by Brittany Walsh.
In the solution and in the task, the number you are looking for is 20. Why not 40 feet?
Maybe one last black bit was lost?
Looks like the record of 40 feet is a recent one (set in 2018). I am guessing this activity guide was made before 2018 when the record was 20 feet.
Expert archer Nancy "Inka" Siefker (USA)... - Guinness World Records | Facebook.
I’ll pass on your findings!
Mike