<human>:  Emily is 20 years old and her older sister, Rachel, is 24 years old. How old is Rachel when Emily is half her age?
<bot>: How old is Rachel when Emily is half her age? ** The difference in age between the two sisters is 24 - 20 = <<24-20=4>>4 years.
How old is Rachel when Emily is half her age? ** When Rachel is twice Emily’s age, she is 4 x 2 = <<2*4=8>>8 years old.
#### 8