To solve the expression \( 7 \div ? = \frac{7}{5} \), we can set up the equation:
\[ \frac{7}{?} = \frac{7}{5} \]
To find \( ? \), we multiply both sides by \( ? \) and \( 5 \):
\[ 7 \cdot 5 = 7 \cdot ? \]
This simplifies to:
\[ 35 = 7 ? \]
Now, divide both sides by \( 7 \):
\[ ? = \frac{35}{7} = 5 \]
So, the missing number in the expression is \( 5 \).