Mary buys a dress that is on sale for 20% off its original price. She uses a store coupon to obtain an additional 30% off the sale price. Mary pays $80 for the dress. What was the original price of the dress? Use an equation to solve.

The original price of the dress is 142.85$

Step-by-step explanation:

Let the original price of the dress be 'x'

After 20% discount the payable amount for the dress is

x-20x/100

=80x/100

=4x/5 first equation (The price of the dress after 20% discount)

Now, after applying the additional sales coupon of 30%, from the first equation we get,

Payable amount for the dress will be 4x/5 - 30x/100*4x/5 (30% of discounted price)

= 400x-120x/5 (100) second equation

But Mary paid 80 $ finally, using second equation we tell us the amount after 30% additional discount.

400x-120x/500 = 80

= 280x=80*500

x = 80*500/280

=1000/7

x = 142.85 $

Hence, the original price is 142.85 $