x=3 is your answer.
To solve this equation we need to isolate the variable.
3x+6=15
So first subtract the number six from both sides. Now the equation should look like this.
3x=9
Then divide both sides by the number 3. So now the equation looks like this.
x=9/3
Simplify 9/3 to 3 and that is your answer.
x=3