第二题

#include<stdio.h>
int main(void)
{
    double x,y;
    printf("Enter x(x>=0):\n");
    scanf("%lf",&x);
        if(x<=50){
            y=0.53*x;
        }
        else{
            y=0.53*50+(x-50)*0.58;
        }
        printf("y=f(%f)=%.2f\n",x,y);
        return 0;
}