a+b+c=345, b=a-25, c=2(a+b), a+b=c/2, inlocuim a+b in prima relatie
c/2+c=345, numitor comun 2
c+2c=690, 3c=690, c=690/3=230, prima relatie devine
a+b+230=345, a+b=345-230=115, inlocuim pe b,
a+a-25=115, 2a=115+25=140, a=140/2=70, b=70-25=45
verificare 70+45+230=345