Răspuns :
4robinete....5ore/ 6robinete....x ore/ x=(6x5):4=7,5 ore
4r......... 5 h
6r.......... xh. ↑↓ ip
4/6=x/5=>x= 4×5/6 = 20/6= 3,(3) h
6r.......... xh. ↑↓ ip
4/6=x/5=>x= 4×5/6 = 20/6= 3,(3) h