If I earned 1,200 dollars in 30 days what was my hourly pay?

You would have to know the number of days that you worked; for example if the 30 days represented a full month and if you did not work Saturdays or Sundays, you probably would have worked only 22 days.

Also, you need to know how many hours per day that you worked.

To calculate hourly pay, you need to know the total number of dollars earned (in this case is $1200) and the total number of hours worked (which is unknown in this case).