A construction company with two black hose has contracted to dig a long trench for drainage pipes the larger black who can dig the entire trench by it self in 12 days the smaller Bracco can dig the entire trench by his self in 14 days the large black oh begins working on the trench by the south but after seven days it is transferred to a different job and a smaller black hole begins working on the trench how long will take the smaller bike how to complete the job