The pie chart given below shows the production of 6 different factories. The total production of all these 6 factories is 15000. The production of a particular factory is shown as a percent of total production of all these 6 factories.

J1 = The value of average production of factory F3 and F6.
J2 = The difference between the production of factory F1 and F4.
What is the value of (J2 - J1)?