One possible probability is 1/10.
Since P(b) = 1/5, we know that there must be some multiple of 5 as the total number of markers.
There cannot be 5 markers in the box; if there is only 1 blue out of 5 markers, it is impossible for there to be any red markers and have a probability less than 1/5.
Using a total of 10 markers, there would be 2/10 blue to have a probability of 1/5. This means there would be 1/10 red. We know nothing about the number of green markers, so there can be as many as we want, in theory. This means the other 7 markers could be green.
It is the first one, (x,y) to (-x,y) because it is going across the y axis from the positive side, so y stays the same but x becomes negative
