Christian and Sue wanted to get a $50.00 bottle of perfume for their mom for her birthday.  Christian had $5.00 saved up and Sue had $7.00.  Christian then mowed 4 of his neighbors' yards, charging $5.00 each, while Sue walked 6 dogs for her neighbors, charging $2.00 per dog.  How much more money will Christian and Sue need to make in order to buy the bottle of perfume for their mom?
Please reason step by step, and put your final answer within \boxed{}.
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