Okay so -5 minus 4 is -9 because you’re basically taking another 4 from -5. Think of the number line. Above 0 (positive numbers) you know that 2 is bigger than 1. Below 0 (negative numbers) it’s flipped. -1 is actually bigger than -2 since it’s closest to 0. When you subtract a negative number from a positive number, you’re essentially adding. So take problem two for example. 1 minus -8 is positive 9. Whenever you add or subtract you’re moving up or down the number line.
