Answer
$4$ is not a solution.
Work Step by Step
For the given number to be a solution of the equation,
the equation must hold true when we substitute the variable with the given number.
$LHS=\displaystyle \frac{1}{2}(4-2)+3=\frac{2}{2}+3=1+3=4$
$RHS=\displaystyle \frac{3}{8}(3\cdot 4-4)==\frac{3\cdot 8}{8}=\frac{3}{1}=3$
$LHS\neq RHS$ , so $4$ is not a solution.