human
Nancy earns $28 for working 4 hours. How many hours does she have to work to earn $70?
assistant
How much does Nancy earn per hour? ** Nancy earns $28/4 = $<<28/4=7>>7 per hour.
How many hours does Nancy have to work to earn $70? ** Therefore, she has to work $70/$7 = <<70/7=10>>10 hours to earn $70.
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