#include<bits/stdc++.h> using namespace std; int T; int a,b,c,d;/* void in(){ a=0,b=0,c=0,d=0; int fh=1; char f=getchar(); if(f=='-'){ fh=-1; } else{ a+=(f-'0'); } while(f=getchar()){ if(!('0'<=f&&f<='9')){ break; } a=a*10+(f-'0'); } a*=fh; fh=1; f=getchar(); if(f=='-'){ fh=-1; } while(f=getchar()){ if(!('0'<=f&&f<='9')){ break; } b=b*10+(f-'0'); } b*=fh;fh=1; f=getchar(); if(f=='-'){ fh=-1; } else{ c+=(f-'0'); } while(f=getchar()){ if(!('0'<=f&&f<='9')){ break; } c=c*10+(f-'0'); } c*=fh; fh=1; f=getchar(); if(f=='-'){ fh=-1; } while((f=getchar())){ if(!('0'<=f&&f<='9')){ break; } d=d*10+(f-'0'); } d*=fh; }*/ int main(){ cin>>T; getchar(); while(T--){ scanf("%d",&a); getchar(); if(getchar()=='-'){ scanf("%d",&b); b*=-1; } else scanf("%d",&b); getchar(); scanf("%d",&c); getchar(); if(getchar()=='-'){ scanf("%d",&d); d*=-1; }else scanf("%d",&d); if(b==d){ printf("0.00000\n"); } else{ printf("%0.5f\n",(d-b)*1.0/(a-c)); } } }