( a+ b + c ) : 3 = 19
a = b + 5
b = c+ 2
a = c + 2 + 5
a = c + 7
( c + 7 + c + 2 + c ); 3 = 19
3c + 9 supra 3 = 19
aducem la acelasi numitor pe 19 il inmultim cu 3
3c + 9 = 57
3c = 57 - 9
3c=48
c = 48 : 3
c =16
b= c + 2
b = 16 + 2
b = 18
a = b + 5
a = 18 + 5
a = 23
verificam
( 16 + 18 + 23): 3= 57 ;3 =19