Dr$.$ Colgate is a dentist to employees an assistant, Miss crest. If Dr$.$ Colgate worked all day at the front desk, she would answer $40$ phone calls. If she worked all day with patients, she could clean the teeth for $40$ patients. If Miss Kress worked all day at the front desk, she could answer $60$ phone calls. If she worked all day with patients, she could clean the teeth of $20$ patients.Has an advantage in blank.