ok, so you start with 48 stuff
you want to divide the 48 stuff into 1 big group and 10 equal small groups
now, its been already determined that the big group will have 8 stuff in it
48-8 = 40
this means we have only 40 left that we need to divide equally within 10 groups
40 divided by 10 = the number of stuff in each small group
any questions?
