i believe that $42 is correct. 27.5 years = 330 months. Divide $5482/330 and deprciation per months is $16.61.
Your new roof was in use 2 months. Mid month comvention means you multiply month my 2 months plus a mid month or half. $16.61 x 2.5 = $41.52. Round uo to $42. There you go.
