A transport service company is running four buses between two towns 50 miles apart. Seating capacity of each bus is 40 passengers. The following particulars were obtained from their books:

Rs

Wages of drivers, conductors and cleaners

2,400

Salaries of office and supervisory staff

1,000

Diesel oil and other oil

4,000

Repairs and maintenance

800

Taxation, insurance, etc.

1,600

Depreciation

2,600

Interest and other charges

2,000

14,400

Actual passengers carried were 75% of the seating capacity. All the four buses ran on all the days of the month. Find out the cost per passenger mile.