a + b + c = 502
b = 3 × a
c : b = 7 rest 2 ==> c = 7×b + 2
c = 7×3×a + 2 = 21×a + 2
inlocuim in prima relatie in functie de a
a + 3 × a + 21 × a + 2 = 502
25 × a = 502 - 2
25 × a = 500
a = 500 : 25
a = 20
b = 3 × 20 = 60
c = 21 × 20 + 2 = 422
Verificare:
20 + 60 + 422 = 502
