Answer
See the explanation below.
Work Step by Step
To solve an equation either in one variable let us say for $x$; we will have to find all values of $x$ that must be satisfied for the equation.
Substitute the value for $x$ that satisfy the equation as a true solution.
Let us take an example: $x=4$ satisfies the expression $4x=16 \implies 4(4)=16$
and $16=16$
Hence, the $4$ is a solution.