Răspuns:
360kl apa............3 robinete.........36minute
360kl apa................4 robinete.......x
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x=3·36:4=27 minute
360kl apa................4 robinete.......27minute
120 kl apa.................4 robinete.........y
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y=27·120:360=9 minute
sau
360:36=10 kl apa curg intr-un minut prin cele 3 robinete
3 robinete.......10 kl apa
4 robinete ........ x
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x=4·10:3=40/3kl curg intr-un minut prin 4 robinete
1 minut(4 robinete) .........40/3 kl apa
y minute(4 robinete) ..........120 kl apa
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y=120:40/3=120·3/40=360/40=9 minute
