The below table shows the number of the music systems that were sold by two companies in the year 2014 to 2017.

What is the difference between the average sale of company A and company B?

1627

Average sale of Company A = $\frac{5640+8412+7148+8424}{4}$ 

                                         = 7406

Average sale of Company B = $\frac{6980+10512+8620+10020}{4}$ 

                                         = 9033

Difference in the average = 9033 - 7406 = 1627