Answer :
First, we should remember the form of a linear equation:
[tex]ax+b=0[/tex]And we want to know if
[tex]\frac{1}{2}x+3=15[/tex]is a linear equation. But as we see that it has the form shown, with a=1/2 and b=-12,
[tex]\begin{gathered} \frac{1}{2}x+3-15=15-15 \\ \frac{1}{2}x-12=0 \end{gathered}[/tex]Then it is a linear equation.