Why is this returning NaN

Question

This code: function AT1 will not work it will return NaN please help
https://code.sololearn.com/WU29Llc6Z8Oz/?ref=app

Answer 1

Repaired and cleaned up little bit
https://code.sololearn.com/We5B6us4ybM6/?ref=app

Answer 2

If you don't understand some changes. Feel free to ask.

Answer 3

Thank you so much!

Answer 4

You'r welcome!