The price of a car is increased by 25%, by how much percent, must the new price of this car be decreased to restore its original price ?

Suppose that the original price of the car = Rs. x 

Then new price of the car

=> (x) + (x ×25/100) = Rs. 5x/4 

To restore the original price, the new price must be decreased by

5x/4 − x = x/4

So required percentage =(x/4)/(5x/4) × 100%

= 20%