What formulas do I use to determine the total surface area of walls to be painted, if I Include the walls in the closets, but ignore windows and doors, and Round to the hundredths place, with 8-foot ceilings. Please show calculations, knowing my room is 8x12 with 8 foot ceilings, and there is a 2 x 3 foot closet. It has a closet door and entry door both are 28x80 in. And a window 2x4 feet.