R=9X 9 bottles multiplicated X cents
R=10(X-2) 10 bottles multiplicated X cents MINUS 2 cents.

Now simply mathematic.
9x=10(x-2)
Bla……
And the result have to be replaced in whatever equation that you want.
Bla….
The result
1.8

i think the result is 20 and not 1.8.
9x= 10(x-2)
9x = 10x -20
x=20

Let's not overcomplicate the problem!

She can buy exactly 9 bottles now. If the bottles cost 2 cents less each, she could buy 1 more bottle.

Well, if the bottles cost 2 cents less each, she'd have 9*2 = 18 cents, which must be the "2 cents less" price per bottle. Therefore, the original price per bottle is 18 + 2 = 20 cents.

So, 9 bottles @ 20 cents each = $1.80 total cash

Alternatively, we could have calculated 10 bottles @ 18 cents each = $1.80 total cash

andreasonlinegr wrote:i think the result is 20 and not 1.8.
9x= 10(x-2)
9x = 10x -20
x=20

Step 4 of the Kaplan method for problem solving: Always double check the question!

Your math is correct, however you let x = the original price per bottle. The question asks how much money she has, not how much each bottle costs.

9 * 20 = 180 cents = $1.80

i think the result is 20 and not 1.8.
9x= 10(x-2)
9x = 10x -20
x=20

ok the result is 20

but remember this

And the result have to be replaced in whatever equation that you want.

so
(10x "20")- 20
= 180 cents