Two fill taps A and B can separately fill a cistern in 45 and 40 minutes respectively. They started to fill a cistern together but tap A is turned off after few minutes and tap B fills the rest part of cistern in 23 minutes. After how many minutes,was tap A turned-off?	Choose the correct option:
A) 9 min
B) 10 min
C) 12 min
D) 7 min
E) None of these
Let A was turned off after x min. Then,   cistern filled by A in x min + cistern filled by B in (x + 23) min = 1   ⇒ x/45+x+23/40=1   ⇒ 17x + 207 = 360 ⇒ x = 9 min.   9 minnswer 9 min
<result>A</result>
Two fill taps A and B can separately fill a cistern in 45 and 40 minutes respectively. They started to fill a cistern together but tap A is turned off after few minutes and tap B fills the rest part of cistern in 23 minutes. After how many minutes,was tap A turned-off?