Samuel is writing a rule for adding numbers with unlike signs. He writes that when
adding two numbers with unlike signs, the sum is always positive. He writes that he
knows this is true because he has tried many examples. The examples he has tried
are below.

-9 + 12 = 3

15 + (-6) = 9

-5 + 8 = 3

-3 + 4 = 1

What can be said about Samuel’s reasoning?