<p>Can someone help me with problem 14, blue book, P919?</p>
<p>Let m=n+3. Since this is divisible by p, m=kp for some integer k. Then, n+10=(n+3)+7=m+7=kp+7. This has to be divisible by p, so 7 must be divisible by p. So answer is p=7.</p>
<p>Thank you!</p>