Ma = (a+b+c) : 3 = 115
a+b+c = 115×3 = 345
a = b/3 => b = 3a
a = c - 75 => c = a + 75
inlocuim in a doua relatie in functie de a
a + 3a + a + 75 = 345
5a = 345 -75
5a = 270
a = 270 : 5
a = 54
b = 3× 54 = 162
c = 54 + 75 = 129
a = 54
b = 162
c = 129
verificare:
(54+162+129) : 3 = 345 : 3 = 115