the pine valley credit union is trying to schedule bank tellers. the credit union is open 8am-6pm and needs a certain number of tellers each hour (see table below). full-time tellers can work 8am-5pm with 12pm-1pm lunch hour or 9am-6pm with 1pm-2pm lunch hour. part-time tellers work 10am-2pm. full-time tellers receive $160 per day and part-time tellers $70 per day. at most four part-time tellers can be hired. please note that the number of tellers must be integer. how can the credit union minimize their daily teller salary cost?