A company has a job to prepare certain number of cans and there are three machines A, B, C for this job. A can complete the job in 3 days, B can complete the job in 4 days and C can complete the job in 6 days. How many days the company will take to complete the job if all the machines are used simultaneously?
- $4$ days
- $4/3$ days
- $3$ days
- $12$ days.