A can finish a work in 12days, B in 9days and C in 2days, B and C start the work but are forced to leave after 3 days. The remaining work was done by A in?
Choose the most appropriate option
A) 10 days  B) 12 days  C) 6 days  D) 7 days  E) 5 days

Rationale: b + c 1 day work = 1 / 9 + 1 / 12 = 7 / 36 work done by b and c in 3 days = 7 / 36 * 3 = 7 / 12 remaining work = 1 - 7 / 12 = 5 / 12 1 / 24 work is done by a in 1 day 5 / 12 work is done by a in 12 * 5 / 12 = 5 days answer is e
Answer: E