Overtime is over 40 so subtract 40 from 54 and get 54-40=14 14 hours hovertime so multipliy usuall pay by 40 (since worked 40 normal hours) then add to overtime pay by 14 hours so
(13.5 times 40)+(13.5 times 1.5 times 14)= 540+283.5=823.5 answer is $823.50
Because, it's literally the same thing mathematically if you worked it out. Though, as I'm sure you're aware, it's just a much shorter and cleaner way of writing out large or small numbers.