Final answer:
In mathematics, a discount is subtracted from the subtotal of an item, while tax and tip are added to the subtotal.
Step-by-step explanation:
In mathematics, when calculating the total cost of an item or service, different financial elements are considered. If we are looking at the subtotal of an item, which is the cost before any additional fees or deductions, one of the three items typically subtracted is the discount. A discount is a reduction in the original price offered, often as a percentage. On the other hand, a tax is an additional charge applied by government policies usually calculated as a percentage of the subtotal, and it is added to the subtotal to get the grand total. Similarly, a tip is an amount paid for services like dining in a restaurant, which is also added to the subtotal. Therefore, a discount is subtracted from the subtotal, while tax and tip are added to it.