(a + b + c) : 3 = 97
a + b + c = 97 × 3 = 291
a/42 = b/25 ==> a = 42b/25
b/15 = c/18 ==> c = 18b/15
inlocuim in suma celor 3 nr. in functie de b
42b/25 + b + 18b/15 = 291 |×75
3 ×42b + 75b + 5×18b = 21 825
126b + 75b + 90b = 21 825
291b = 21 825
b = 21 825 : 291
b = 75
a = 42 × 75/25 = 42 × 3 = 126
c = 18 × 75/15 = 18 × 5 =90
Verificare:
(126 +75 + 90) : 3 = 291 : 3 = 97