You need to find "dollars per hour". So you need to know the total dollars and the total hours.
You already know the total dollars ... it's 54.
What are the total hours ? 2-1/2 plus 4-1/4 . Can you add those ?
Once you add up the total hours, divide ($54) divided by (total hours).
The quotient is the number of dollars she earns for each hour she works.