3-5

#include<stdio.h>
int main(void)
{
    double value1,value2;
    char op;
    printf("Type in an expression:");
    scanf("%lf%c%lf",&value1,&op,&value2);

    if(op=='+')
        printf("=%.2f\n",value1+value2);
    else if(op=='-')
        printf("=%.2f\n",value1-value2);
    else if(op=='*')
        printf("=%.2f\n",value1*value2);
    else if(op=='/')
        printf("=%.2f\n",value1/value2);
    else
        printf("Unknown operator\n");


    return 0;
}