Nancy earns $28/4 = $<<28/4=7>>7 per hour.

Therefore, she has to work $70/$7 = <<70/7=10>>10 hours to earn $70.

# Answer

10
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Nancy earns $28 for working 4 hours. How many hours does she have to work to earn $70?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
10
Nancy earns $28 for working 4 hours. How many hours does she have to work to earn $70?
train