由题知：(y+m)/(x+n)=c 设c为常数
分别将X=3时,Y=5；X=5,Y=11代入得：(5+M)/(3+N)=(11+M)/(5+N)解得 m=3n+4
将m=3n+4代入：(x+n)/(y+m)=c 解得x = (y+2n+4)/c