Will mark as brainliest

-1 + 2 = 1

1 + (-2) = -1

-1 - 2 = -3

1 - (-2) = 3

Step-by-step explanation

When you subtract use keep change change

Rule 1 when you add : If the signs are the same add the numbers and take the sign of the bigger number.

Rule 2 when you add : If the signs are different subtract the numbers and take the sign of the bigger number.

I wanted to help you understand and i hope i did that!