Final answer:
To solve for u in the equation 9 + x + u + (*) = x = 5, subtract x and 9 from both sides of the equation, then subtract (*) from both sides. The answer is u = -4 - (*).
Step-by-step explanation:
The given equation is 9 + x + u + (*) = x = 5. To solve for u, we need to isolate it on one side of the equation.
Step 1: Subtract x from both sides of the equation to get 9 + u + (*) = 5.
Step 2: Subtract 9 from both sides of the equation to get u + (*) = -4.
Step 3: Subtract (*) from both sides of the equation to get u = -4 - (*).
Therefore, the answer is u = -4 - (*) where (*) represents any unknown value given in the question.