You have to tackle it a bit at a time.
3/7 were blue. So what fraction was green?
That is the first bit.
It is tricky but draw a 4*4 grid
The top left corner is blank
the heading in the top boxes are blue, green, total
the headings down the left side are kept, given, total
The bottom right-hand box will be the total number of buttons.
Now try filling it in, some will be fractions and some numbers but you can then work out the numbers from the fractions later.
