The percentage distribution of the number of tires of different brands produced in a year by a certain factory is shown in a pie chart with the following distribution: Avon
21%, Cooper
20%, Dunlop
15%, Good year
12%, Firestone
14%, Hankook
7%, and Continental
11%. If the total number of tires sold is
1350,

what is the difference between the average number of Avon and Firestone tires sold together and the average number of Good year and Dunlop tires sold together?