#include<iostream>
#include<iomanip>
using namespace std;
int main(){
    double x,a,y,b;
    cin>>x>>a>>y>>b;
    cout<<fixed<<setprecision(2)<<(a*x-b*y)/(a-b);
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
double x,a,y,b;
int main(){
    cin>>x>>a>>y>>b;
    printf("%.2lf",(x*a-y*b)/(a-b));
	return 0;
}

#include #include using namespace std; int main(){ double x,a,y,b; cin>>x>>a>>y>>b; cout<<fixed<<setprecision(2)<<(ax-by)/(a-b); return 0; }

经典问题——牛吃草。

#include<bits/stdc++.h>
using namespace std;
double x,a,y,b;
int main(){
    cin>>x>>a>>y>>b;
    printf("%.2lf",(x*a-y*b)/(a-b));
	return 0;
}