“…She solved problem as "Hasan works one day and then has three days off before he works again and Ahmet works one day and then has four days off before he works again. According to this Hasan works on 1,4,7,10,13,16,19,22,25,28 March and Ahmet works on 1,5,9,14,19,24,29 March. She found that they work together on 19 March.…”