The question asks to identify which number line correctly models the subtraction $12 - 18$ and also to compute the result of $12 - 18$.

Step 1: Interpret the problem

The subtraction $12 - 18$ can be interpreted as starting at 12 on the number line and moving 18 units to the left, since subtracting a number moves left on the number line.

Step 2: Analyze the number lines

1. First number line: The arrow starts at $12$ and moves to the right, indicating an addition or a positive change.
2. Second number line: The arrow starts at $12$ and moves to the left, indicating a subtraction or a negative change.

Since $12 - 18$ involves moving to the left, the second number line is the correct model for this subtraction.

Step 3: Perform the subtraction

$12 - 18 = -6$ The result of the subtraction is $-6$.

Conclusion

• The second number line correctly models $12 - 18$.
• The result of the subtraction $12 - 18 = -6$.

Would you like more details or have any further questions?

Here are five related questions:

1. What does subtracting a larger number from a smaller number represent?
2. How do you graphically represent addition on a number line?
3. What are the rules for subtracting negative numbers?
4. How can number lines help visualize absolute value?
5. What is the significance of zero on a number line during subtraction?

Tip: When subtracting numbers, always check if you're moving left (subtracting) or right (adding) on a number line to visualize the result.