a household uses the given appliances
calculate the electric bill with info as given

Dear Student,

1 unit= 1kWh 
​​​​​​It means 1 unit is equal to consumption of 1 kW/ 1000W for 1 hr.

$$\begin{gathered} U\sin g energy=(number of items)\times \left(power\right)\times \left(time\right) \\ a) 400 W for 10 hrs consumes 400\times 10=4000W hr \\ b) two electric fans will consume 2\times 80\times 6=960 W hr \\ c)five electric tube will consume 5\times 18\times 6=540 W hr \\ total consumption each day=4000+960+540=5500 W hr=5.5 kW hr= 5.5 units \end{gathered}$$

$$\begin{gathered} Each day bill=5.5\times 3= Rs. 16.5 \\ Bill for 1 month(30 days)=16.5\times 30= Rs. 495 \end{gathered}$$

Regards,