After you remove the 6 from the left side, you will have an equation of the form $4x = \text{(number)}$. What operation will undo multiplying by 4?

Once you find a value for $x$, substitute it back into $4x + 6$ and make sure it equals 18.

In a Desmos expression line, type (18 - 6) / 4 and look at the numerical result; this is the value of $x$ that satisfies $4x + 6 = 18$.

Start with the equation:

To isolate the term with $x$, undo the $+6$ by subtracting 6 from both sides:

which simplifies to:

Now you have $4x = 12$. To solve for $x$, divide both sides by 4 (the coefficient of $x$):

Simplify the fraction to find the value of $x$.

Simplifying $\dfrac{12}{4}$ gives $3$, so:

Therefore, the correct answer is 3.