[tex] \frac{1}{4} [/tex]din72=72:4=18
[tex] \frac{1}{8} [/tex]din72=72:8=9
[tex] \frac{1}{3} [/tex]din72=72:3=24
72-(18-9+24)=21
72-51=21(creioane verzi)
-------------------------------------------------------succes!------------------------------------