The least common mutiple for 8 and 2 is 8 beacause all you have to do is mutiple by 2 and 8 and you get the same least number that is your answer. Sorry for my sucky explaining i hope this helps a little.
If it's 40 minutes for just 5 papers, we need to figure how many minutes it would take to grade just 1. So you have to divide 40 by 5 which is 8. Then 8 time 30 which is 240.
