Chapter 9 - Basic Algebra - 9.2 Adding and Subtracting Signed Numbers - 9.2 Exercises - Page 641: 100

a) $-18,20,-5,4$ Zero does not affect the addition b) $2,-10,-3,7$ Zero does not affect the subtraction

a) $$-18 + = -18$$ $$20 + 0 = 20$$ $$0+(-5) = -5$$ $$0+4 = 4$$ Zero does not affect the addition. b) $$2-0 = 2$$ $$0-10 = -10$$ $$-3-0=-3$$ $$0-(-7) = 7$$ Zero does not affect the subtraction.