. Completați lanţul de calcule: 4.

Răspuns:
a) 2/7 -> 3/7 –> 7/7 = 1 = 5/5 -> 2/5 -> 3/5
b) 3/11 -> 9/11 -> 0/11 = 0/6 -> 5/6 -> 3/6
c) 3/28 -> 3/4 ->19/12 -> 76/45 -> 684/450
coroana?