#### Answer

$ED = 50$

#### Work Step by Step

$\overline{ED}$ joins the midpoint of $\overline{TU}$ and also the midpoint of $\overline{VU}$. According to the triangle midsegment theorem, if a line segment joins two sides of a triangle at their midpoints, then that line segment is parallel to the third side of that triangle and is half as long as that third side.
Knowing this information, we can deduce that $\overline{TV}$, which is the third side, is parallel to $\overline{ED}$, which is the line segment that joins the midpoints of the other two sides of the triangle. It also means that $\overline{TV}$ is two times the length of $\overline{ED}$. So, if we know $TV$ or $VT$, then we can find $ED$:
$TV = 2(ED)$
Let's plug in the values we know:
$100 = 2(ED)$
Divide both sides of the equation by $2$ to solve for $ED$:
$ED = 50$