How do you solve $3x+18=-18$?

Hint: In this question we have been given with a linear equation for which we have to find the value of the term $x$ by isolating the term $x$. We will rearrange the terms in the expression by keeping the variable term $x$ on the left-hand side while keeping the constant values on the right-hand side and simplifying the terms to get the required solution.

Complete step by step solution:
We have the given equation as:
$\Rightarrow 3x+18=-18$
Now we will take the similar terms on the same side, on transferring the term $18$ from the left-hand side to the right-hand side, we get:
$\Rightarrow 3x=-18-18$
On simplifying the terms in the right-hand side, we get:
$\Rightarrow 3x=-36$
On transferring the term $3$ from the left-hand side to the right-hand side, we get:
$\Rightarrow x=\dfrac{-36}{3}$
Now the term $-36$ can be written as $-12\times 3$ therefore, on substituting, we get:
$\Rightarrow x=\dfrac{-12\times 3}{3}$
On cancelling the common term from the numerator and denominator, we get:
$\Rightarrow x=-12$, which is the required solution.

Note: To verify whether the value found is correct or not, we will substitute it in the left-hand side of the expression. On substituting $x=-12$, we get:
$\Rightarrow 3\left( -12 \right)+18$
On multiplying the brackets, we get:
$\Rightarrow -36+18$
On simplifying, we get:
$\Rightarrow 18$, which is the right-hand side therefore, the answer is correct.
It is to be remembered that the equation given above is a linear equation which has only one variable which is $x$. It is to be remembered that when a term which is addition or subtraction when transferred across the $=$ sign, it becomes a term in subtraction and addition respectively.