Answer:
air for 
 is not a pair of equivalent fraction.
Explanation:
Fraction of a ham sandwich left = 

Fraction of a turkey sandwich left = 

Now we find, 
Fraction of sandwich that he eat.
Fraction of a ham sandwich Joseph eat = 

Fraction of a Turkey sandwich Joseph eat = 

Now the pair of fraction we have are
Pair 1: 

Pair 2: 

Now, Equivalent fraction are those fractions which has equal simplest form.
Clearly above pair of fractions are already in simplest form.
So, pair 1 of fraction are not equivalent fractions.
Therefore, Pair for 
 is not a pair of equivalent fraction.