cu metoda grafica a mersului invers

|____|____|____| vasul
|____|____| apa
|__|__|__|__|
|__|__|__| 100 litri
100 l = 3/4 = > 4/4 = 400/3 litri
400/3 l = 2/3 => 3/3 = 400/3·3/2 = 1200/6 = 200 litri (capacitatea vasului)