Amber is on a family cell phone plan with the other 3 members of her family. the family gets 868 shared cell phone minutes a month, and each family member is limited to his or her equal share of the minutes. the only free calls are calls between family members. how many minutes per day can amber talk on her cell phone with her friends during a 31-day month, without going over her share of the minutes? a. 217 b. 6 c. 7 d. 28