To calculate the discount rate in Fred's promotion ("buy 4 get 1 free"), follow these steps:

1. Regular cost without promotion:

   • For 5 T-shirts, the total regular cost would be:
     $5 \times 15.97 = 79.85$

2. Cost in the promotion:

   • You only pay for 4 T-shirts, so the cost is:
     $4 \times 15.97 = 63.88$

3. Amount saved:

   • The discount amount is the difference between the regular cost and the promotional cost:
     $79.85 - 63.88 = 15.97$

4. Discount rate as a percentage:

   • The discount rate is the amount saved divided by the regular total cost, multiplied by 100:
     $\left(\frac{15.97}{79.85}\right) \times 100 \approx 20\%$

Thus, the discount rate is approximately 20%.

Would you like more details or have any questions?

Here are 5 related questions:

1. How do you calculate the price for multiple items with a discount applied?
2. What is the formula for finding the percentage of a number?
3. How does buying in bulk usually affect the cost per item?
4. How can you calculate total savings over time with recurring promotions?
5. What are some other ways companies use promotions to encourage sales?

Tip: When calculating percentage discounts, always compare the discount to the original total price to get an accurate rate.