题目

阅读理解CassieWarren and Jesse Jones will always have a great story to tell their kids about thekindness of strangers and how one stranger in particular made their weddingplanning much sweeter.Afew weeks ago, as Warren was addressing wedding invitations for her upcomingwedding, she mistakenly used an old address for her aunt and uncle in nearbyEugene, Oregon. But when a stranger received the misaddressed mail, she didn'tjust throw it in the garbage like many people would have done. Instead, shereturned the invitation, along with a sweet note and $20 as a wedding present.Thesender also wrot已知一个数与5的和为-2，这个数是______．