What is the result of 15 + (-8)?

• A. 23
• B. 7
• C. -8
• D. 15

Answer: (B)

When you add a negative number, you’re essentially subtracting a positive amount. So 15 + (-8) means you start at 15 and move 8 units to the left on the number line, which is the same as 15 − 8. That equals 7. This also follows the rule that when numbers have opposite signs, you subtract the smaller magnitude from the larger and keep the sign of the larger magnitude, which here is the positive 15. So the result is 7. The other results would come from adding the magnitudes (23) or not subtracting at all (15) or taking only the negative part (-8), which aren’t what this expression does.