To solve the equation \( \frac{15^?}{15^7} = 15^{12} \), we can use the properties of exponents.
Using the quotient rule of exponents, we have:
\[ \frac{15^a}{15^b} = 15^{a-b} \]
So, applying that to our equation:
\[ 15^{? - 7} = 15^{12} \]
Since the bases are the same, we can set the exponents equal to each other:
\[ ? - 7 = 12 \]
Now, we can solve for \( ? \):
\[ ? = 12 + 7 \] \[ ? = 19 \]
Therefore, the missing number is:
19