Răspuns :
a sa zicem ca e numarul iuliei
(a+ax3):2=26
a+ax3=26x2
a+ax3=52
a+a+a+a=52
52:4=13
a=13
(13+13x3):2=(13+39):2=52:2=26
(a+ax3):2=26
a+ax3=26x2
a+ax3=52
a+a+a+a=52
52:4=13
a=13
(13+13x3):2=(13+39):2=52:2=26