25) The L'Orue is a currency that has only two coins, worth 8 and 11 cents. What is the largest amount that cannot be paid exactly?

$\begin{array}{lll}\text { (A) } 58 \text { cents } & \text { (B) } 61 \text { cents } & \text { (C) } 87 \text { cents }\end{array}$

(D) there are arbitrarily large amounts that cannot be paid exactly

(E) none of the above answers is correct.
25) The answer is $\mathbf{( E )}$. Indeed, 58 or 61 cents cannot be paid, while $87=8 \cdot 4+11 \cdot 5$ can be paid. On the other hand, all multiples of 8 can be paid, all numbers of the form $8 k+1$ that are greater than or equal to 33, all numbers of the form $8 k+2$ that are greater than or equal to 66, all numbers of the form $8 k+3$ that are greater than or equal to 11, all numbers of the form $8 k+4$ that are greater than or equal to 44, all numbers of the form $8 k+5$ that are greater than or equal to 77, all numbers of the form $8 k+6$ that are greater than or equal to 22, and all numbers of the form $8 k+7$ that are greater than or equal to 55.

Therefore, the maximum excluded number is $69=77-8$.