>>518
#include <stdio.h>
#include <stdlib.h>
typedef struct{int n,d;}frac;
frac add(frac x,frac y){x.n=x.n*y.d+y.n*x.d;x.d*=y.d;return x;}
frac sub(frac x,frac y){x.n=x.n*y.d-y.n*x.d;x.d*=y.d;return x;}
frac mul(frac x,frac y){x.n*=y.n;x.d*=y.d;return x;}
frac dvd(frac x,frac y){x.n*=y.d;x.d*=y.n;return x;}
int main(){frac x,y;char buf[BUFSIZ];fgets(buf,BUFSIZ,stdin);
sscanf(buf,"%d %d %d %d",&x.n,&x.d,&y.n,&y.d);
printf("%d/%d + %d/%d = %d/%d\n",x,y,add(x,y));
printf("%d/%d - %d/%d = %d/%d\n",x,y,sub(x,y));
printf("%d/%d * %d/%d = %d/%d\n",x,y,mul(x,y));
printf("%d/%d / %d/%d = %d/%d\n",x,y,dvd(x,y));return 0;}