Grace and her children went into a grocery store and where they sell bananas for $0.50 each and mangos for $0.75 each. Grace has $7.25 to spend and must buy a minimum of 13 bananas and mangos altogether. If Grace decided to buy 8 mangos, determine all possible values for the number of bananas that she could buy. Your answer should be a comma separated list of values. If there are no possible solutions, submit an empty answer.