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 $
