Question

14 vaci consuma in 5 zile 840 kg hrana. Cate kg de hrana vor consuma 10 vaci in 12 zile? Folositi metoda de 3 compusa

Answer 1

14 vaci......840 kg ......5 zile
10 vaci.......x kg .........12 zile

x =$\frac{12*840*10}{14*5}=1440kg$ consuma cele 10 vaci in 12 zile

Answer 2

Avem regula  de 3 compusa ... adica:
14 vaci  ...  5 zile ... 840 kg
10 vaci  ...12 zile ...   x   kg
 descompunem problema in 2 probleme mai simple:
I.     14 vaci ... 840kg
       10 vaci ...   x kg   sunt marimi d.p.
=> x=(10*840):14= ... (kg) ;
II.     5 zile ... 840kg 
      12 zile ...    x kg    sunt marimi d.p.
⇒   x=(12*840):5= ... (kg) ;
compus... 
$x=\frac{10\cdot12\cdot840}{14\cdot5}=\frac{100800}{70}=1440(kg)$