 
<translate> Ka yi la'akari da wannan tambayar. Bututu biyu A da B za su iya cika rijiyar ruwa a cikin minti 20 da 30, kuma bututu na uku C zai iya zubar da shi a cikin minti 40. Yaya tsawon lokacin da za a yi a cika rijiyar idan an buɗe duka uku a lokaci ɗaya? Zaɓuɓɓuka: (A) 17 da 1/9 (B) 17 da 1/3 (C) 17 da 7 (D) 17 da 1/9 (E) 17/1 Menene tsarin tunani mataki-mataki don isa ga amsar: (C)? <eng> Consider the question. Two pipes A and B can fill a cistern in 20 and 30 minutes respectively, and a third pipe C can empty it in 40 minutes. How long will it take to fill the cistern if all the three are opened at the same time?
Options:
(A) 17 1/9
(B) 17 1/3
(C) 17 1/7
(D) 17 1/9
(E) 17 1/1
 What is the step-by-step reasoning process to arrive at the answer: (C)? 