We need two numbers from {15, 7, 11} to complete 8 + __ = __.<br><br>
&bull; Try 7: 8 + 7 = 15. Both 7 and 15 are in the set. &#10003;<br>
&bull; Try 11: 8 + 11 = 19. 19 is not in the set. &#10007;<br>
&bull; Try 15: 8 + 15 = 23. 23 is not in the set. &#10007;<br><br>
Final Answer: 8 + 7 = 15