Answer:
the time taken by Emily to bake the cookies alone is 7.2 hours
Explanation:
The time taken by Emily to bake the cookies alone is shown below:
Given that
Christine can bake cookies in 9 hours
And, if her friend Emily is also helps her so it only takes 4 hours to bake the cookies
Now based on the above information
Hence, the time taken by Emily to bake the cookies alone is 7.2 hours