 Adding or subtracting a finite area from an infinite area leaves it infinite. Adding a shape with infinite area to another shape of the same infinite area leaves the total area unchanged, and subtracting a negative infinite one from a positive one or vice versa is similar. But \((+\infty) + (-\infty)\) cannot be meaningfully evaluated; nor can \((+\infty) - (+\infty)\). If you take one infinitely large region, and remove an infinitely large region, you might be left with nothing, or a positive region, but you might still be left with an infinitely large region; or if the region you subtracted was larger than the original region, you might be left with a negative region—even an infinite negative region.