 
 <translate> A pipe can fill a cistern in 18 minutes whereas the cistern when fill can be emptied by a leak in 20 minutes. When both pipes are opened, find when the cistern will be full?
Options:
(A) 17
(B) 180
(C) 70
(D) 120
(E) 12 Now, let's think a bit. Some random thoughts: <hau> Bututun zai iya cika rijiyar a cikin mintuna 18 yayin da rijiyar idan ta cika za a iya zubar da shi ta hanyar zubewa a cikin mintuna 20. Idan aka buɗe bututun biyu, ka san lokacin da rijiyar za ta cika? Zaɓuɓɓuka: (A) Goma sha bakwai (B) 180 da kuma (C) 70 (D) 120 (E) 12 Yanzu, bari mu ɗan yi tunani. Wasu tunani bazuwar: 