1005: estimation of the earth's population carrying capacity

1005： Estimation of the earth's population carrying capacity

The time limit : 1000 ms         Memory limit : 65536 KB
Submission number : 98483     Passing number : 55255

【 Title Description 】
Suppose that the new resources on the earth increase at a constant rate . According to this calculation , The earth's existing resources plus new resources are available for xx Billion people live aa year , Or for yy Billion people live bb year .

In order to achieve sustainable development , Avoid resource depletion , How many billion people can the earth feed at most ？

【 Input 】
a line , Including four positive integers x,a,y,bx,a,y,b, Two integers are separated by a single space .x>y,a<b,ax<byx>y,a<b,ax<by, Each integer is not greater than 1000010000.

【 Output 】
A real number zz, It means that the earth supports... At most zz Hundreds of millions of people , Round to two decimal places .

【 sample input 】
110 90 90 210
【 sample output 】
75.00
 

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