Question

Thirty-one books are arranged from left to right in order of increasing prices. The price of each book differs by $2 from that of each adjacent book. The price of the book at the extreme right is equal to the price of the middle book plus a book adjacent to the middle one. Give an expression for the cost of the $n$th book in terms of $n$

Answer 1

The answer for this problem is 2 since it is not specified whether it is adjacent to the right or adjacent to the left.
If it is adjacent to the right, the answer is:

p (k) = 2 * p(1) + 2 * k

If the is adjacent to the left, the answer is:

P (k) = 2 *p(1) +2 * (k-2)