Answer:
40 + -40 =0 (your answer)
2538494 + -2538494 = 0 (example)
4 + -4 = 0 (example)
-18 + 18 = 0 (example)
-82 + 82= 0 (example)
just as long as the first number and the second number are the same, and one is negative and the other is positive, added together the two numbers will equal zero.
