You are correct. If we compare only the size of the two numbers +7 and -9, paying no attention to sign, we see that 9 is a larger number than 7; thus -9 has a larger absolute value than +7.
The rule for adding two numbers that have the same sign (that is, both + or both -) is: To add numbers of like sign, add the absolute magnitudes of the numbers and attach the common sign. Thus, ( + 2) + ( + 3) = ( + 5), and ( − 2) + ( − 3) = ( − 5). When the signs of the numbers are the same, simply add the numbers and attach the common sign to the sum.
