A can do a piece of work in 20 days, B can do a piece of work in 12 days,both are working together for 3 days after A left the job,then how many days B requires to complete the remaining work?	Select.
A) 6 days	B) 5 days	C) 3 days	D) 7 days	E) 12 days

Rationale: first take lcm of ( 20,12 ) = 60 ; total work = 60 ; a ' s one day work = 60 / 20 = 3 ; b ' s one day work = 60 / 12 = 5 ; one day work of both a + b = 3 + 5 = 8 ; total work completed in 3 days = 8 * 3 = 24 ; remaining work is = 60 - 24 = 36 ; remaining work completed by b in = 36 / 12 = 3 days . answer = c
Answer: C