If $x=3$, which of the following is true?
(A) $2 x=5$
(B) $3 x-1=8$
(C) $x+5=3$
(D) $7-x=2$
(E) $6+2 x=14$
When $x=3$,

$$
\begin{aligned}
& 2 x=2 \times 3=6 \\
& 3 x-1=3 \times 3-1=8 \\
& x+5=3+5=8 \\
& 7-x=7-3=4 \\
& 6+2 x=6+2 \times 3=12
\end{aligned}
$$

Of the given answers, $3 x-1=8$ is the only one of the given equations which is true when $x=3$.

ANSWER: (B)