Notam:
1r 3h - primul robinet deschi 3 ore
2 r 4h - al 2 lea robinet deschis 4 ore
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1r 3h + 2 r 4h = 820 l
1r 6h + 2r 2h = 914 l | x 2
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1r 3h + 2 r 4h = 820 l
1 r 12 h + 2 r 4 h = 1828
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1 r 9 h = 1008 l
1 r 1 h= 1008 : 9 = 112 litri intr-o ora
1 r 112 x 3 + 2 r 4h = 820 l
1 r 336 + 2r 4h = 820
2r 4 h = 820-336 = 484 l
2 r 1 h = 484 : 4 = 121 l