Question

Today, everything at a store is on sale. The store offers a 20% discount.

1. The regular price of a T-shirt is $16. What is the discount price?
2. Write an expression for the discount price of x dollars.
3. The discount price of a hat is $20. What is the regular price?

Answer 1

1. $16-20%= 12.8 US$

2. $x-20%=x

3. >>>>>?

Explanation:

A 20% discount means that you subtract 20% of the normal price. Suppose the normal price is $100. 20% of this is $20. Subtract this from $100 and you have the new price---$80.

Note that "subtracting 20%" is the same as multiplying by 0.8----the general formula is:

discount price = normal price * (1-d) , where d is the decimal equivalent of the percentage discount.

From the example above:

discount price = normal price * (1-d) = 100(0.8)

to go the other way, simply rearrange the formula:

normal price = discount price / (1-d)