#include <iostream>
using namespace std;

int main(int argc,char* argv[])
{
 float concentration = 0;
 float real_concentration = 0;
 
 concentration = (60/80)*100;
 cout<<"Weight percent = "<<concentration<<"%\n";
 real_concentration = (float)60/(float)80*100;
 cout<<"Real Weight percent = "<<real_concentration<<"%\n";
}

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float형 사용시 형변환을 안 하면 정수연산이 된다.