If the perimeter of the triangle shown is 21 , what is the value of $x$ ?
(A) 3
(B) 7
(C) 8
(D) 13
(E) 16

![](https://cdn.mathpix.com/cropped/2024_04_20_6027bc27089ed4fc493cg-027.jpg?height=219&width=290&top_left_y=1316&top_left_x=1357)
In terms of $x$, the sum of the three side lengths of the triangle is $x+x+1+x-1=3 x$. Since the perimeter is 21 , then $3 x=21$ and so $x=7$.

ANsWER: (B)