Answer: z=-27 *The answer must have negative sign.*
Step-by-step explanation:
subtraction property of equality is subtracting the same number from both sides of an equation does not change the equation.
a-c=b-c
addition property of equality is adding the same number to both sides of an equation does not change the equation.
a+c=b=c
first, subtract by 9 both sides of an equation.
z+9-9=-18-9
then, simplify by equation.
18+9=27
It change positive to negative sign.
z=-27
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