加油折扣精确版(ง•̀_•́)ง，总是部分正确

Question

#include <stdio.h>
float count_discount(int x, float y,float pay)
{
    float sum;
    if (pay<200)
    {
        sum = y * 0.3;// 每升优惠3毛
    if (x == 5)  // 星期五每升额外优惠1毛 
        sum += y * 0.1;
    }
    else
    {
        y = y - (200 / 8.38);
        sum = y * 0.3;// 每升优惠3毛
        if (x == 5)  // 星期五每升额外优惠1毛 
            sum += y * 0.1;
    }
    sum = (int)(sum*100.0 + 0.5) / 100.0;
       return sum;
}
float coupondiscount(float a)
{
    if (a>200)
    {
        return 20;
    }
    else 
    {
        return 0;
    }
}
int main()
{
    int t, x;
    float y;
    float pay, discount;
    scanf("%d", &t);
    while (t--)
    {
        scanf("%d", &x);
        scanf("%f", &y);
        pay =(8.38 * y);
        discount = count_discount(x, y,pay);
        if (pay >= 200)
            pay -= 20;
        pay = pay - discount;
        printf("Order amount: %.2f\n", (int)(8.38 * y*100.0+0.5)/100.0);
        printf("E-coupon discount amount: %.2f\n", coupondiscount(8.38 * y));
        printf("Discount amount: %.2f\nPayment amount: %.2f\n", discount, (int)(pay*100.0 + 0.5) / 100.0);
    }
    return 0;
}

总是部分正确，不知道错在哪里＼(◎o◎)／！大家看看能不能改改？是逻辑上的问题，还是精度的问题

Answer 1

请把代码用 “代码块” 贴出来，大家才好帮你。