When you subtract a negative, it automatically becomes a positive. That's why when we were making it simpler above, we canceled out the two minus signs (subtractions sign and negative sign) to make a positive 4. That's why we added a positive instead of subtracting a negative.
A negative plus a positive will get bigger. That's why -6 + 4 = -2. The -2 is larger than -6 when you look at it on a number line. It's closer to 0 and the positives.
