a+b+c=68
a=b-0.8 ;si a =c :3 deci c=3a ;c =3(b-0.8 ) inlocuim in prima relatie pe a si c
b -0.8 +b +3(b-0.8 )=68
b -0.8 +b +3b -2.4 =68
5 b =68 +0.8 +2.4
5b= 71.2
b = 14.24
a =14.04 -0.8 =13.44
c =3.* a ;
c =3 *13.44 =40.32 ;13.44+14.24+40.32=68
13.44+14.24+40.32 totul supra 3 =22.666666