I agree.. this is painful ..
To add to what Sci@phy told you, take a closer look at this
float calculate_mile_per_hour(float miles, float minutes);
{
float mile_per_hour;
miles_per_hour = (miles * 60)/minutes);
return (mile per hour);
}
First of course, remove the semi-colon from all of your function definitions. Now, you declare your variable as
mile_per_hour .. then on the next line you have
miles_per_hour and you are trying to return
mile per hour ... Your variable names ALL need to be exactly the same.. and you cannot have spaces in a variable name.
Read your code very carefully, and go through your compile errors and fix one line at a time. You need to read and understand your compile errors.