Five men are working to complete a work in 15 days. After five days 10 women are accompanied by them to complete the work in next 5 days. if work is to be done by women only, then in how many days could the work be over if 10 women have started it ? a. `10\ d a y s` b. `12\ d a y s` c. `15\ d a y s` d. `18\ d a y s`