Chapter R - Section R.2 - Operations on Real Numbers - R.2 Exercises - Page 19: 2

Negative

The sum of two negative numbers is a negative number. When we add together two numbers with the same sign, we are adding their absolute values. The sum will have the same sign as the given numbers, which is negative in this case. For example, $-6-3=-(|6+3|)=-(|9|)=-(9)=-9(\lt0)$