C语言小白问题 ①代码如图1 运行结果如图2 为什么第三行显示0.0，哪里错了

C语言小白问题 ①代码如图1 运行结果如图2 为什么第三行显示0.0，哪里错了②或者像下文这样写，哪里错(语法错误不算。。)?为什么运行结果(如图3)不一样?

#include <stdio.h>
#define gasolineconversionfactor 3.785
#define distanceconversionfactor 1.609
int main()
{
float miles,gallons;

printf("Please enter the number of miles traveled.\n");
scanf("%f",&miles);
printf("Then please enter the number of gallons of gasoline.\n");
scanf("%f",&gallons);
printf("The number of miles per gallon is:%.1f\n",miles/gallons);
printf("In American way,it will be%.1f\n",gallons*gasolineconversionfactor/miles*distanceconversionfactor*100);
return 0;
}

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