To find the missing number in the equation \( 7 + __ + 10 = 29 \), you can start by simplifying the equation.
First, combine the known numbers:
\[ 7 + 10 = 17 \]
Now, substitute that back into the equation:
\[ 17 + __ = 29 \]
Next, to find the missing number, subtract 17 from 29:
\[ __ = 29 - 17 \]
\[ __ = 12 \]
So, the missing number is \( 12 \).
Thus, the completed equation is:
\[ 7 + 12 + 10 = 29 \]