Subtraction of signed numbers
To subtract signed numbers:
1. Change the sign of the second number.
2. Use the rule for adding.
(-9) - (+5) = (-9) + (-5) = -9 -5 = -14
(+12) - (-8) = (+12) + (+8) = 12 +8 = 20
(-19) - (+7) - (-6) = (-19) + (-7) + (+6) = -19 -7 +6 = -26 +6 = -20
