Question

http://prntscr.com/arz64i

Can someone explain step three?

Don't understand why we did 1/12 twice?

Answer 1

inch^2 = inch * inch

so the conversion factor needs to be there twice

Answer 2

in other words,

1 inch = (1/12) feet
1 inch^2 = (1/12) * (1/12) feet

Answer 3

Thank you!
@Vocaloid