210×3=630 baloane in total
r+g+a+v= 630
r=g
r+g+v=420
420+a=630
a=630 -420
a=210 baloane albastre
a+v=290
210+v=290
v=290-210
v= 80 baloane verzi
r+g+80=420
2r+80=420
2r=420- 80
2r= 340
r=340÷2
r=170 baloane rosii
g=r=170 baloane galbene
verificare
170+170+210+80=630