A row of houses all share a community space where they put up their clotheslines. There are 2 clotheslines for every house on the street. On the street, there are a total of 11 children and 20 adults. Each child currently has 4 items of clothing on the clotheslines and each adult currently has 3 items of clothing on the clotheslines. If each clothesline can hold 2 items of clothing and all of the clotheslines are full, how many houses are on the street?
Please reason step by step, and put your final answer within \boxed{}.
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