#include<stdio.h> int main() { double n1 = 0.0; double n2 = 0.0; char opt = '0'; while (scanf("%lf %c %lf", &n1, &opt, &n2) != EOF) { switch (opt) { case '+': printf("%.4lf+%.4lf=%.4lf", n1 ,n2 ,n1+n2); break; case'-': printf("%.4lf-%.4lf=%.4lf", n1 , ...