the reason for this is that -630 is simplified to 5, -so 1/5 is really 126/630, (630 divided by 5 is 126) - and so 2/5 is 126 x 2 =252/630 - there are only 3 parts left, and if 1p has more parts than 5p, -then 1p takes up 2/5 of the bag -and 5p takes up 1/5 of the bag