Thabo owns exactly 140 books, and each book is either paperback fictio

Hi manish0709,

Both examples relate a variable to a second variable by multiplication (in this case, by 2), so the basic math concept is the same. In the Thabo question, we're dealing with the NUMBER of two items, whereas in this question, we're dealing with the PRICES of two items.

"The regular price of each solid oak door was twice the regular price of each hollow pine door"

This means that if we multiply the regular price of a hollow pine door, then we'll have the regular price of a solid oak door. For example, if the price of a regular hollow pine door is $5, then the price of a regular solid oak door would be $10. Thus:

(Price of regular oak door) = 2(Price of regular pine door)

GMAT assassins aren't born, they're made,
Rich