According to the question:
6Monday + Tuesday + Wednesday + Thursday + Friday + Saturday=4200
Monday=1200
Sunday=1500
Monday + Tuesday + Wednesday + Thursday + Friday + Saturday=4200×6=25200
1200 + Tuesday + Wednesday + Thursday + Friday + Saturday=25200
Tuesday + Wednesday + Thursday + Friday + Saturday=24000
Adding Sunday to this:
Tuesday + Wednesday + Thursday + Friday + Saturday + Sunday=24000+1500=25500
To find the average =625500=Rs. 4250