Question

There are 20 lb of nuts. They are to be packaged in bags, with 1 1/2 of nuts in each bag. How many pounds will be left over?

Answer 1

I suppose it's 1.5 lb per bag.
To find the number of bags you can fill, you have to know how many times 1.5 "fits in 20", which is just a simple way to say: you need to divide 20 by 1.5.

When you do that, you will not get an integer. It is a number of wholes (=entire bags) and a rest. The rest is the number of pounds that is left.