If 20% of an electricity bill is deducted, then Rs 100 is still to be paid. How much was the original bill?

If 20% of an electricity bill is deducted, then Rs 100 is still to be paid. How much was the original bill?

Explanation

Let the original bill be x. After deduction of 20%, the remaining amount is Rupees 100. Expressing given information in mathematical form.

x - 20% of x = 100

Solving the mentioned mathematical equation to find the value of x.

x - 20/100x = 100

x - x/5 = 100

Taking L.C.M., which is 5.

5x - x = 5*100

Performing subtraction and multiplication.

4x = 500

Performing division to find the value of x.

x = 500/4

x = Rupees 125

So, the original bill is Rupees 125.