以下程序的功能是计算f(x,y,z)=(x+z)/(y-z)+(y+2*z)/(x-2*z)的值，请将程序补充完整。#includefloat f(float x,float y){float value;value =;return value;}main（）{float x,y,z,sum;scanf("%f%f%f",&x,&y,&z);sum=f(x+z,y-z)+f();printf("sum=%f\n",sum);}