Bill is calculated as per the following conditions
1) upto 200 calls(0-200 ) are free
2 ) 200 to 500 1Re/Call
3) Above 500 2 Re/Call
4 ) 100 Rs Rental Extra
Eg: for 250 calls ,
Bill = 100(Rental)+0*200 (free upto 200) +50*1( above 200 1 re on 50 calls) = Total 150Rs