What is the difference between number of laptops (both Dell and Lenovo) sold by store Q and total number of Lenovo laptops sold by store R and S together

Directions (next five questions) :  Refer to the pie charts and answer the given questions.

Distribution of number of laptops 

(both Dell and Lenovo) sold by 5 stores in 2011

Total number = 4500

Distribution of total number of Dell laptops sold 

by 5 stores : Total number = 2400

Directions (next five questions) : What will come in place of question mark (?) in the given number series