Question 935004
{{{(n+8)}}} is the mid-segment of a triangle (also called a midline) is a segment joining the midpoints of two sides of a triangle and its length is half the length of the third side {{{ 3n+7}}}

or we can say the length of he third side {{{ 3n+7}}} is equal to twice the length of the mid-segment {{{(n+8)}}}

{{{ 3n+7=2(n+8)}}}

{{{3n+7=2n+16}}}

{{{3n-2n=16-7}}}

{{{highlight(n=9)}}}=> your answer