Answer :
Here is how I would solve this problem:
52/4 = 13
13.00 for 1 hours worth of work
6.50 for 30 minutes of work
13*3=39.00
Therefore, she would have to work 3 hours to earn 39.00
52/4 = 13
13.00 for 1 hours worth of work
6.50 for 30 minutes of work
13*3=39.00
Therefore, she would have to work 3 hours to earn 39.00