percentage unite (problem solving for primary school)

Question

I am trying to come up with an interesting problem to show my students how the percentage units work. In their book I can only find the problems for ex: "the interesting rate has risen from 2% to 3%. How big is the increase a) in percentage unites b) in percent." What do you think of a problem like this: "Sam's wages has risen for 3,4% and Maria's wages has risen for 4,5%. How much less has Sam's wages risen compared to Marias rise? (calculate it in percentage unites and in percent)". Apart from the question if this problem is well defined, I also want to ask you, guys, if you have a more interesting problem where one can see better when and why we use the percentage units and when the percentage. Thank you in advance.