M can do a piece of work 5 days less than that of P. M and P began to work together but M leaves after some days and P completed the remaining work in 12 days. Number of days after which M left the job-

• A. $$ 5{7 over9}$$
• B. $$ 6{7 over9}$$
• C. $$ 7{7 over9}$$
• D. $$ 11{7 over9}$$
• E. None of these