I need help on part b please. part a is james i already know that.

Answer:
$150
Step-by-step explanation:
Well, lets see. I'm no expert but I'm in Advanced Math 7th Grade so I could possibly help.
We have to figure out how much each person is getting per hour for part a.
We can use this formula:
James: 102/12= 10
Julie: 120/15= 8
I really have no clue so my guess would be this.
Using a table: We can figure out how much James would get for a 15 hours based on getting 102 for 12.
Therefore according to my 7th grade brain the answer is $150 for doing 15 hours of yard work for James.
I hope this helped!