Use the information to answer question below

.........................     Departments
...........................                      P                Q                R
Sales value...............                           N23,400
Selling expenses..........      1,100         N1,400         N1,280
Administrative expenses...N1,400       N1,000          N1,020
Cost of sales.............      N6,900....    N6,700           N5,500

Sales value of department Q doubles that of p, which is 1/3 of R. Depreciation which amounts to N1,800 is to be apportioned among the three departments in the ratio 3:5:7 respectively.

What is the sales value of department R?