The bookshelf will not fit because the angle of the bookshelf is too small, the angles of the pentagon add up to exactly 540 degrees so the bookshelf is off by 30 degrees
Yes, the porch is 12 feet wide. If 1 inch = 2 feet, and if she makes the porch 6 inches wide, then you multiply the 6inches by 2, since 1 inch is equal to 2 feet.