What must be added to 5 and 1/3 to get a sum of 9?

Answer 1

9 - 5 1/3 = ?

Answer 2

4 and 6/9

Answer 3

Nope. What happened to the fractions?

4 + 5 = 9
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9 - 5 1/3 =
8 3/3 - 5 1/3 = 3 2/3