(a+b+c)/3=15,(6)
15,(6)=(156-15)/9=141/9=47/3
a+b+c=47
1,(6)=(16-1)/9=15/9=5/3
0,8(3)=(83-8)/90=75/90=5/6
(5/3+5/6+5/6)/3=(5/3+10/6)/3=(5/3+5/3)/3=(10/3)/3=10/9
47/3+10/9=(47*3+10)/9=(141+10)/9=151/9=16,(7)
verificare
(a+5/3+b+5/6+c+5/6)/3=(47+5/3+10/6)/3=(47+5/3+5/3)/3=(47+10/3)/3=151/9