练习2-2

#include<stdio.h>
int main(void)
{
    double x,y;
    printf("Enter x:\n");
    scanf("%lf",&x);
    if(x <= 50){
        y = x * 0.53;
    }
    else{
        y = 26.5 + (x - 50)*0.58;
    }
    printf("y=%.2f\n",x,y);
    return 0;
}