O lucrare=10 muncitori*2ore=15muncitori*xore
x=2*10/15=2*2/3=4/3 =1si1/3 ore=1ora si 20de minute
as quicky as that!!
regula de trei simpla pntru marimi invers proportionale
10m...........2ore=120minute
15m........................n minute, n=10x120/15=80minute=1h20min