discounted books = D..
.3 *D = bargain books = B..
NOW B = .18 T..
so \(.3D = .18*T\) so \(\frac{D}{T} = \frac{.18}{.3} = .6\)or 60%
D
_________________

I personally not an individual too accustomed to construing books, then I must acknowledge that you are one of the greatest (and fastest) techniques to come across a writer and whether or not his style turns your perception.

Let 10 books have been discounted
Bargain books = 3

3 represents 18%
1 represents 18/3
10 represents 18/3*100 = 60%

Approach is similar to that used by [b]chetan2u , I have just plugged in some numbers...[/b]
_________________

We can let the total number of discounted books = d and let the total number of books in the store = n.

We need to determine what percent of the books in the store are discounted or d/n x 100 = ?

Since 30 percent of the books that have been discounted are called bargain books, bargain books = 0.3d

Since bargain books make up 18% of the total books in the store, bargain books = 0.18n

Thus, we can equate 0.3d and 0.18n and isolate d/n.

0.3d = 0.18n

30d = 18n

d/n = 18/30 = 3/5

Thus d/n x 100 = 3/5 x 100 = 60 percent.

Answer: D
_________________

\(\frac{(0.3X)}{T}* 100 = 18\)

\(\frac{X}{T}* 100 = 60%\)

REMEMBER WE ARE ASKED THE PERCENTAGE OF DISCOUNTED BOOKS i.e., which is \(\frac{X}{T}*100\) i.e., 60%.

Hence D is the correct choice.

The fact that "they are priced below $4" is completely irrelevant, right?

If the total number of books in the store is 100, then 18% is 18.

18 books are bargain books, which are 30% of the discounted books. So there are 60 discounted books. 60 is 60% of 100.

Agree, give kudos! Have a better method, please comment.

Bargain = 18% of total = 18/100 of total
Bargain = 30% of discounted = 3/10 of discounted

So 100% is the reciprocal of 30% (10/3) multiplied by the percentage of the total

18/100 * 10/3 = 180/300 = 60/100

Hi Guys, could anyone tell me why you would divide 18/30 instead of 30/18?

Because it asks: “what percent of the books in the store are discounted?” That is discounted books divided by total number of books, or d/n. To find d/n from the equation 30d = 18n; you would first divide each side by 30 and then by n.
_________________

Let the total number of books = 100
bargain books = 18 % of 100 books = 18
Let total books that was discounted = X

We need to find the percentage of total books that were discounted?

Since bargain books = 30 % of X and we know the total bargain books, we can determine X

0.3X = 18
The X = 60

(60/100)*100 = 60% of the total books in the store were discounted.