Add: \( -13+(-15)+7 \)

To solve \( -13 + (-15) + 7 \), we can first add the two negative numbers: \(-13 + (-15) = -28\). Now we add \( 7 \) to the result: \(-28 + 7 = -21\). So, the final answer is \(-21\). For a quick mental math trick, remember that combining two negatives results in a larger negative, while when you add a positive, you’re essentially climbing up the number line back toward zero! Common mistakes often occur when people forget to account for the signs. Always pay attention to whether you're combining positive or negative numbers and watch out for the pesky minus signs!