It is given that pieces of 3 1/4 inch are needed to be cut from 20 metal rods of 19 inch each. And disregard waste.
So the proper fraction for 3 1/4 is:

The number of pieces possible from 1 rod are:

So discarding the waste, 5 pieces can be cut from one 19 inch rod.
Hence from 20 rods, the number of pieces possible are:

Hence 100 pieces are possible.