Question

How to derive to original price from discount price?

Answer 1

Discount price = mp-discount
If gain % is given then

Discount price is also called sp
So let cp be x and gain % be y
Formula = x + y% of x = sp

Answer 2

You can do it by assuming original price be x.
And, then whatever be the discount, say y.

Then
x-y% of x = Discount price.
Solve and you will get the original price.

Hope you will find it helpful.