Question

Find EF in the trapezoid

Answer 1

EF is halfway between AD and BC.

Using the midpoint formula:
$4x=\frac{(x+6)+57}{2}$
⇒$4x=\frac{x+63}{2}$
⇒$8x=x+63$
⇒$7x=63$
⇒$x=9$

EF is $4x=4(9)=36$