The difference in age between the two sisters is 24 - 20 = <<24-20=4>>4 years.

When Rachel is twice Emily’s age, she is 4 x 2 = <<2*4=8>>8 years old.

# Answer

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<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Emily is 20 years old and her older sister, Rachel, is 24 years old.  How old is Rachel when Emily is half her age?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
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Emily is 20 years old and her older sister, Rachel, is 24 years old.  How old is Rachel when Emily is half her age?
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