I always start an explanation by just telling a student how to do something. For a lot of students, starting from a working example is the easiest way to learn. I don't think talking in circles around the problem is a very good way to lead a student (especially a struggling student) to the answer. In my experience that often turns students off.
My example showed how to use the Arduino platform to do a simple program. The assignment however was about writing a function, kelvinTemperature(celcius), which my program did not do.
Given my example as a starting point, Luther (or any other student in the class) would needed to write a short function to accomplish the conversion, rather than do the arithmetic inline. I believe using a user written function is the point of this assignment.
So no, turning in such a simplistic answer, which did not accomplish the basic requirements of the assignment would not have earned the student an A.