What does it mean when two functions are inverse of each other?

Angle mno is s rotated 180 degrees counterclockwise about the origin to form angle m’n’o’. which statement shows the measure of angle m’n’o’?

Given: klmn is a parallelogram m? n=3m? k, lf ? kn , ld ? nm kf=2 cm, fn=4 cm find: lf, ld

Including 6% sales tax, an inn charges $135.68 per night. find the inns nightly cost