Answer:
Question 1
The error is in step 2. They have subtracted [tex]3x[/tex] from the left side of the equation, yet only subtracted 3 from the right side.
Questions 2 & 3
Solve:
[tex]3(3x + 6 + x) = 1[/tex]
Apply the distributive law [tex]a(b + c) = ab + ac[/tex] :
[tex]\implies 9x + 18 + 3x = 1[/tex]
Collect and combine like terms:
[tex]\implies 9x + 3x+ 18 = 1[/tex]
[tex]\implies 12x + 18 = 1[/tex]
Subtract 18 from both sides:
[tex]\implies 12x + 18 - 18 = 1 - 18[/tex]
[tex]\implies 12x = -17[/tex]
Divide both sides by 12:
[tex]\implies \dfrac{12x}{12}=-\dfrac{17}{12}[/tex]
[tex]\implies x=-\dfrac{17}{12}[/tex]