Suzie is building a bird house using 1x6's,1x4's, #8 Wood Screws and wood glue. The bird house will have a 10" long 1x6 in the back, and 7" long 1x6 in the front. The sides will be made of 1x4's both 7" in length as well. The top will be flat, butted up to the back, with a 1" overhang and constructed of a 1x6 5 1/4" in length. How long will the 1X6 on the bottom need to be if it is flush in front and placed under the back 10" long piece?