To find the missing number in the equation \(4x + 10 = __x + 10\), we can compare both sides of the equation.
Since both equations have "+ 10" on each side, we can simplify the equation to:
\[ 4x = __ x \]
This means that the missing number must be 4. Therefore, the complete equation is:
\[ 4x + 10 = 4x + 10 \]
So, the missing number is 4.