So, it depends. Imma give you two answers, all of which are the same at the end. They just have different ways to do it.
1. So, it's $9 per hour, or $9 per 60 min
You can write a ratio: 9/60 = n/1
In this case you have to divide 9 by 60 cause
60/60 = 1
And n=0.15
Answer: you earn 15 cents per min.
2.$9 = 900 cents
900 cents divided by 60 minutes = 15 cents in a minute.
Hope this helps love!! :)