To solve the equation \( 12 + u = 22 \), we need to isolate \( u \).
We can do this by subtracting 12 from both sides of the equation:
\[ u = 22 - 12 \]
Calculating the right side gives us:
\[ u = 10 \]
Thus, the value of \( u \) that is a solution to the equation is \( u = 10 \).