Write a proportion that can be used to find the part if you know the base and the percent. then, solve the proportion.

This scenario is mostly found during a store sale where they offer discounts.

Assuming: Original price = 90 ; discount rate = 25%

Discount value = Original price * discount rate
Discount value = 90 x 25% = 22.50

Since 25% is the discount, you only need to pay 75% of the original price.

Discounted Price = original price * (100-25)% = 90 x 75% = 67.50

If you make it a little more clear i can answer it