We can compare by converting Johnny's reading time into the same unit of Jacky's, hours.
There are 60 minutes in an hour, so use this:
15 < 20, so Johnny read faster. This is 5 pages faster per hour than Jacky.
There are 60 minutes in an hour, so use this:
15 < 20, so Johnny read faster. This is 5 pages faster per hour than Jacky.