1. Multiply the original price by 25% (or 0.25) to get the discount amount.
2. Subtract the original price from the discount amount to get the discount price. For example, if the original price of the goods is 100 yuan, then the discount amount is 100*0.25=25 yuan. The discounted price is 100-25=75 yuan.
3. So after 15% discount on China Merchants Bank's credit card, the amount to be paid is 75% of the original price.