Exercitiul 12
Va rog cat se poate de rapid!

Răspuns:
Ma=(a+b+c)/3
Ma=20 si 1/3=(20·3+1)/3=61/3
a+b+c=61/3·3=>a+b+c=61
12,(5)=(125-12)/9=113/9
9,(6)=(96-9)/9=87/9
113/9+87/9+⁹⁾c=⁹⁾61
113+87+9c=549
9c=549-200=>c=349/9=>c=38,(7)