9. Write a C++ definition of function Fahrenheit ToCelsius(t), which re turns the Celsius equivalent of Fahrenheit temperature t. Using com mon mathematical notation, the result is (5/9) (t -32). Be sure to write your definition in correct C++ notation. Do not change the parameter, t. Make this function do exactly its job and nothing more. A heading is given double FahrenheitToCelsius (double t) 10. Write a C++ definition of function absval(r), which returns the ab- solute value of real number . For this exercise, do not se library functions abs or fabs. Make abval do exactly its job and nothing more. Do not change the parameter, . A heading is given double absval (double x) . Write a C++ definition of function favorite(y), which returns true if y is 3, 5 or 7, and returns false otherwise. Make favorite do exactly its job and nothing more. Do not change the parameter, y. A heading is given. double favorite(double x)