What must be subtracted from `-7` to obtain `-15`?

Options

A. `-8`
B. `8`
C. `-22`
D. `22`

Answer

To solve the question "What must be subtracted from -7 to obtain -15?", we can follow these steps:

### Step 1: Set up the equation
Let \( x \) be the number that must be subtracted from -7. According to the problem, we can write the equation:
\[ -7 - x = -15 \]

### Step 2: Isolate \( x \)
To find \( x \), we need to isolate it on one side of the equation. We can do this by adding \( x \) to both sides and adding 15 to both sides:
\[ -7 - x + x = -15 + x \]
This simplifies to:
\[ -7 = -15 + x \]

### Step 3: Add 15 to both sides
Next, we add 15 to both sides of the equation to isolate \( x \):
\[ -7 + 15 = x \]
This simplifies to:
\[ 8 = x \]

### Step 4: Conclusion
Thus, the value of \( x \) is 8. This means that 8 must be subtracted from -7 to obtain -15.

### Final Answer
So, the answer is:
\[ \text{8 must be subtracted from -7 to obtain -15.} \]

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