#include<bits/stdc++.h> using namespace std; int T; long long 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(){ ios::sync_with_stdio(0); cin.tie(NULL);cout.tie(NULL); cin>>T; getchar(); while(T--){ cin>>a; getchar(); if(getchar()=='-'){ cin>>b; b*=-1; } else cin>>b; getchar(); cin>>c; getchar(); if(getchar()=='-'){ cin>>d; d*=-1; }else cin>>d; if(b==d){ printf("0.00000\n"); } else{ printf("%0.5f\n",(d-b)*1.0/(a-c)); } } }