Notam cu a,b,c numerele rationale:
a+b+c = 252
a/5 = b/7= c/12
a = 5b/7
c= 12b/7
inlocuim in prima ecuatie
5b/7+b+12b/7 = 252 |×7
5b+7b+12b = 1 764
24b = 1 764
b = 1 764:24
b = 73,5
a = 5×73,5/7 = 367,5/7 = 52,5
c = 12×73,5/7 = 882/7 = 126
Verificare:
52,5+73,5+126 = 252
a = 52,5
b = 73,5
c = 126
