Another tough Algebra Problem... please help me?

Question

A shop owner marked the selling price of a washing machine such that he would make a 40% profit. He later sold it at a 20% discount and made a profit of $72. What was the original selling price of the washing machine.

Answer 1

Let x = original price.

Then 1.4x = 40% markup price

Now we sell it a 20% discount or at 80% of the markup price or
(0.80)(1.4x)

So
(0.80)(1.4x) - x = 72

1.12x - x = 72

0.12x = 72

x = $600 original price

Now prove our answer.

1.4x = $840 marked up price

0.8(1.4x) = $672 price at 20% discount

$672 - $600 = $72 profit after 40% markup and 20% discount.
.

Answer 2

First you have to remember that the multiplication sign (x) means "of" when you are dealing with a question that has to do with percents (%).

So first you do it backwards,
$72 divided by 0.20 = 360,
$360 divided by 0.40 = 900.
therefore the original price was $900.

to check answers,
$900 x 0.40 = 360,
$360 x 0.20 = 72.

I hope my explanations are clear. I'm pretty smart so I'm pretty confident with my answer.
I hope I helped.