ANSWER
Melanie uses 31 and a half pencils per hour
EXPLANATION
If she uses 14 pencils in 4/9 of an hour, we want to find how many pencils does she use in 1 hour:
[tex]1\times(14\colon\frac{4}{9})=14\colon\frac{4}{9}=14\times\frac{9}{4}=\frac{126}{4}=\frac{63}{2}=31\frac{1}{2}[/tex]