Răspuns:
12 tractoare........12 ore
1 tractor........12*12=144 ore
4 tractoare .........144÷4=36 ore
2.
2robinete.........60 ore
1 robinet.....60*2=120 pre
5robinete........120÷5=24 ore
3.
6 robinete.......60 ore
1 robinet.......60×60=3600 ore
3 robinete.......3600÷3=1200 ore
4.
10 tractoare ......44 ore
1 tractor......44*10=440
8 tractoare...... 440÷8=55 ore