6.16

 #include<stdio.h>  main()  {      int x,y,z;      for(x=0;x<=20;x++)        {            for(y=0;y<=33;y++)            {            3*y+5*x+z/3.0==100;            z=100-x-y;        if (5*x+3*y+z/3.0==100&&z+x+y==100)        {            printf("x=%d,y=%d,z=%d\n",x,y,z);        }        }        }        }