Help preparing for the SHSAT?

I need help with a SHSAT question?

• I have been studying for the SHSAT for a long time now and as most of you know the SHSAT is a very important exam. I came across a very difficult question while I was studying in my Princeton Review book. The question was: If 10 magazines cost d dollars, how many magazines can be purchased for 3 dollars? You guys might be thinking that this is an easy problem but it is actually pretty difficult. Choices: (F) 3d/10 (G) 30d (H) d/30 (J) 30/d (K) 10d/3 The answer that I came up with was (K) because 10 X D / 3 will give you how many magazines can be purchased for 3 dollars. The answer that the book gave was (J) 30/d which I don't understand at all. This answer doesn't make any sense! If any of you can please explain how J is the answer I would really appreciate it because a similar question might appear on the SHSAT.

• Answer:

  Cost of 1 mag = d/10 cost of 3 mag = 3 divided by d/10 or 3 X 10 /d or 30/d