Track / Stage 4 / 13 of 340 #273 of 1964

If the perimeter of the triangle shown is 21 , what is the value of $x$ ?

Pick one

A 3 B 7 C 8 D 13 E 16

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Official solution

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)

Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic, difficulty and ordering added by this site.