(a+b+c)/3=14
a+b+c=14 ori 3
a+b+c=42
a+7=b
3c=b
a+a+7+c=42
2a+7+c=42
2a+c=42-7
2a+c=25
3c=b=>c=b/3 dar b=a+7=>c=(a+7)/3
2a+(a+7)/3=35
2a ori 3/3+(a+7)/3=35
6a+a+7 totul supra 3=35
7a+7=35 ori 3
7a+7=105
7a=105-7
7a=98
a=98/7
a=14
a+7=b=>14+7=b=>b=21
3c=b=>3c=21=>c=21/3=>c=7
