[tex]\begin{gathered} 3x=x+10 \\ \text{Here, we subtract x from both sides of the equation} \\ 3x-x=x-x+10 \\ 2x=10 \\ \text{Divide both sides of the equation by 2} \\ \frac{2x}{2}=\frac{10}{2} \\ x=5 \end{gathered}[/tex]
Hence, the correct option is C: x=5
