Baking Muffins Engineering Problem

Stacey and Marcy are baking muffins for a party. If Stacey bakes all the muffins by herself, she will need 12 days. If Marcy bakes all the muffins by herself, she will need 9 days. It takes a total of 10 days for Stacey to first work on the task and then Marcy to continue the task. How many days did Stacey use and how many days did Marcy take?

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