Sure, let's rewrite "a - b" as an addition problem. To do that, we can use the rule that subtracting a number is the same as adding its opposite. So, "a - b" can be rewritten as "a + (-b)".
Now, let's choose some negative integers for a and b. Let's say a = -5 and b = -3.
So, a - b becomes -5 + (-(-3)). Simplifying further, we have -5 + 3, which equals -2.
Therefore, when a = -5 and b = -3, a - b is equal to -2