Replica plating is done to look for the genotypes of exconjugants, and this presentation doesn't talk about conjugation, F-, F+, or Hfr strains. You have to know those things before this exercise. Your textbook probably doesn't go into replica plating too much, so the "Solution" to the problem below gives a bit of information on that.
Here's the exercise. Try it before looking at the solution!
And now - the solution!