C++ hundred chicken problem of integer real number difference

A hundred chicken problem. Each rooster is 5 RMB, the hen is 3 RMB, every 3 chicks is 1 RMB, and 100 RMB is for 100 chickens.

Exhaustive method

Code 1

int main(){
    
    
    int x,y,z;
    cout<<"cock\t"<<"hen\t"<<"chick\t"<<endl;
    for(x=0;x<20;x++){
    
    
        for(y=0;y<33;y++){
    
    
            z=100-x-y;
            if(x*5+y*3+z/3.0==100){
    
    
                cout<<x<<'\t'<<y<<'\t'<<z<<endl;
            }
            }
        }
    }

cock    hen     chick   
0       25      75
4       18      78
8       11      81
12      4       84

Code 2

int main(){
    
    
    int x,y,z;
    cout<<"cock\t"<<"hen\t"<<"chick\t"<<endl;
    for(x=0;x<20;x++){
    
    
        for(y=0;y<33;y++){
    
    
            z=100-x-y;
            if(x*5+y*3+z/3==100){
    
    
                cout<<x<<'\t'<<y<<'\t'<<z<<endl;
            }
            }
        }
    }

cock    hen     chick   
0       25      75
3       20      77
4       18      78
7       13      80
8       11      81
11      6       83
12      4       84

Why does this happen?
Verify

    int x=10;
    int y = 3;
    double a=10.0;
    double b=3.0;
    cout<<x/y<<endl;
    cout<<a/b<<endl;
    cout<<x/b<<endl;

3
3.33333
3.33333

Dividing two integers will round off the decimal.
So the difference between code 1 and code 2 3.0 and 3 is the case.
This is actually a difficult solution for every 3 chicks 1 ¥