Javier is constructing a door for his son’s tree house. The dimensions of the rectangular door are 6a2 - a + 2 feet and 3a2 + 5 feet. He wants to cut out a square from the door to insert a glass panel, as per the diagram below. The glass panel will have a height of a - 3 feet. After Javier removes the square for the glass panel, how much of the door will be made from wood