Answer:
27 weeks
Explanation:
first you would figure out how long one oz. of hair gel would last her. You would do this by dividing 21 by 14. 21/14 is 1.5. Next, if 1 oz. lasts 1.5 weeks, and there is a 18 oz bottle, then all you need to do is multiply 18 by 1.5. 18 times 1.5 is 27. Therefore, an 18 oz. bottle of hair gel would last Emily 27 weeks.