C - Write a Function that Accepts a Score for a Driver's License

(Please include comments in the code).
It is required that in all assignments a Cast should be used to convert float to int.

1- Write a function that accepts a score for a driver's license facility, an int or a float, and returns a letter. If the score passed in is less than 75, then the letter returned is an F for Fail. Otherwise, the letter returned is a P for Pass.

The logic in this function must use a ternary operator.

2- Write a function that accepts a numeric reading from an industrial instrument, an int or a float, and returns an int. If the reading passed in falls between 40 and 80, the number returned is a 1. If the reading passed in falls between 100 and 140, then the letter returned is a 2. If the reading passed in falls between 180 and 200, then the letter returned is a 1. A value of 0 is returned if a reading outside these values is passed in.

The logic in this function must use if - else statements.

3- Write a function that accepts a score for a class, an int or a float, and returns a letter grade. If the score passed in is equal to 4, then the letter returned is an A. If the score passed in is equal to 3, then the letter returned is a B. If the score passed in is equal to 2, then the letter returned is a C. If the score passed in is equal to 1, then the letter returned is a D. Otherwise, the letter returned is an F.

The logic in this function must use a switch.

Prompt the user for input in the main function of the program for each of the above described functions, call each function, and display the result of each function.

Naming convention of functions and variables is left up to you.

as a tip for understanding the concept laid out that I have to follow:

I have to keep in mind the difference between the comparison operator in C, ==, and the assignment operator, =. When making boolean comparisons, makes sure that I use == and not use =.

Assignment:

int x = 5;
float fNum = 20;
total = subTotal + foodExpenses;

Comparison:

if ( x == 5)
printf("x is %d", x);
else if ( x == 20 )
printf("x is %d", x);

I don't want to have: if (x = 5).