Answer:
[tex]x=-3[/tex]
Step-by-step explanation:
Given the equation
[tex]7=|3x+9|+7[/tex]
1. Use Addition property of equality, add -7 to both sides:
[tex]7-7=|3x+9|+7-7\\ \\0=|3x+9|[/tex]
2. The absolute value of the number is 0 if and only if the number is 0, so
[tex]3x+9=0[/tex]
3. Use Addition property of equality, add -9 to both sides:
[tex]3x+9-9=0-9\\ \\3x=-9[/tex]
4. Use Division property of equality, divide both sides by 3:
[tex]\dfrac{3x}{3}=\dfrac{-9}{3}\\ \\x=-3[/tex]
