Question 3 In response to customer complaints about rising prices of food items, a supermarket responds by making the following offer:

For every $10 of purchase, the customers will earn $1 worth of coupons and this way they will end up making twice as much as the supermarket.

If the supermarket makes $500 worth of total sales to all customers taken together, how much will it need to restrict its costs to so as to honour the offer?