Vac n' sew will give customers $100 for a used vacuum cleaner, regardless of condition, when they purchase a new vacuum or sewing machine. this essentially reduces the price by $100. what is this type of discount called?

Trade-in allowance

Explanation:

A trade-in allowance is a type of discount in which the price of a good is reduced by the value of a another good that the buyer gives to the seller.

In this question, we have a trade-in-allowance because buyers give a product (a used vacuum cleaner) valued at $100 in exchange for a discount by the same amount of the total price of the new vacuum that they want to buy.