A company offers two salary plans for its new employees. Plan A offers a fixed salary of $2,000 per month plus a commission of $50 for each sale made. Plan B offers a fixed salary of $1,500 per month plus a commission of $100 for each sale made. For how many sales will the two plans provide the same total monthly income for an employee? Let's think step by step and output the final answer within \boxed{}.
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