Answer:
- [tex]\Large\boxed{\sf{x=4}}[/tex]
Step-by-step explanation:
You have to find the value of x, to isolate it on one side of the equation.
[tex]\sf{3x+9=21}[/tex]
First, you have to subtract by 9 from both sides.
[tex]\sf{3x+9-9=21-9}[/tex]
Solve.
Subtract.
21-9=12
Rewrite the problem down.
3x=12
Then, you divide by 3 from both sides.
3x/3=12/3
Solve.
Divide the numbers from left to right.
12/3=4
[tex]\Longrightarrow: \boxed{\sf{x=4}}[/tex]
The answer should have a "positive sign".
- Therefore, the correct answer is x=4.
I hope this helps, let me know if you have any questions.
