Since every 2 students have to share a stapler, then:
1 stapler has to be shared by 2 students, so:
S staplers has to be shared by X students, so:
2S = X
You do the same with R and X and G and X.
You also know that S+R+G=65 so then you can solve it in a straightforward way.
Why exactly?I have no idea how to do this. If i add 2+3+4= 9. So number of students has to be a multiple of 9.