Answer:
in both cases the flyer was presented to the barber before the service was provided.
a) no, because Karl was informed about the mistake and the real price and could then still have decided to take his business elsewhere. but if he then agreed to still have the service performed under the now updated conditions, then that is what the "contract" is basing on.
he has no grounds to claim the other price afterwards.
b) no, because the service provider saw the flyer information, did not object to or correct the information right away, but performed the service instead. now the "contract" is based on that agreement based on the conditions of the flyer.
Robots can know things instantly as humans can not we at least think about it for 1-90 seconds before we come up with with our answer same as I had to do for yours.
C. is your answer ...........
Ask for suggestions, be kind, be sympathetic to better understand the issue