Hi, i have the below question:

Jenny misplaced her personal organiser while at work. She placed a reward notice on the staff notice board. The following day one of her colleagues, Samantha, returned her organiser. Samantha was not aware of the reward notice. Overjoyed at the return of her personal organiser, Jenny said she would pay Samantha the full amount of the reward. Subsequently Jenny changes her mind. Is Samantha entitled to demand the offered reward?

It has been answered on this site but i am confused as it is a promise but jenny did also verbally tell her she will pay her.