Răspuns :
n = 12*5+r = 60+r
0 < r < 12
[tex]r\in\{1,2,3,4,5,6,7,8,9,10,11\} \\ \\ 60+r\in\{61,62,63,...,71\}[/tex]
0 < r < 12
[tex]r\in\{1,2,3,4,5,6,7,8,9,10,11\} \\ \\ 60+r\in\{61,62,63,...,71\}[/tex]