Edward the plumber is replacing a pipe in a bathroom wall.  He needs to use 40 feet of copper pipe to complete the job.  For every 5 feet of pipe, Edward must use one tightening bolt, and for every bolt, he uses two washers.  He buys a bag of 20 washers for the job.  After he completes the bathroom job, how many washers will be remaining in the bag?
Please reason step by step, and put your final answer within \boxed{}.
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