Data Flows- Power Query M code- Get the percentage using two columns- Cheater code

I want percentage of days a student missed out of the school year. 

Add a custom column and put:

if [DaysEnrolled] <> null and [DaysEnrolled] <> 0 then

    Number.Round(([UNEXCUSED_ABS] / [DaysEnrolled]) * 100, 2)

else

    0