Getting a percentage discount

Question

I'm currently working on a website which has a list of products with predefined prices.

The owner of the website would like me to add two membership levels.

• Membership Level A will see a 15% increase in prices.
• Membership Level B will see the current defined prices with no increase.

Since it's easier to offer discounts rather than markups, I decided to take a route where I would increase all prices by 15% and offer a discount to Membership Level B.

However, what that discount would be to get the current prices is a mystery.

$A + 15% = $B

But

$B - 15% ≠ $A

Answer 1

Using the following formula

% decrease = -100 * ( (B - A) / |A| )

A = Initial Number
B = Final Number 

If Product is prices at $100, an increase of 15% would make it $115. But decrease 15% from $115 would get you $97.75.

Using an online calculator gives me a value of 13.04348% decrease.