Răspuns :
g+r =28
r= g : 3 => g = 3r
g + r -= 28
3r + r = 28
4r= 28
r = 28 : 4
r = 7
g =3r =>g = 3 x7 => g = 21
r= g : 3 => g = 3r
g + r -= 28
3r + r = 28
4r= 28
r = 28 : 4
r = 7
g =3r =>g = 3 x7 => g = 21