10 tube lights of 20 watt each are used in house for 5 hours daily calculate the bill of one month for the electricity with the rate of rupees 7.30 per unit.

1 BULB=20 WATT
10 BULB=200*10
             =20000 WATT OR 20KILOWATT
TIME=5HOURS
​ENERGY=POWER *TIME
                 20KW * 5 HRs
               =100KWH OR 100 UNITS
1 DAY ENERGY= 100 UNITS
30 DAYS ENERGY= 100 *30 = 3000 unit 
1UNIT=7.30 RUPEES
3000 UNIT = 21900 RUPEES

HOPE THIS HELP