in attachments
Hello again,
(5) I guess we must assume that the figure is a parallelogram.
In a parallelogram, the diagonals bisect each other.
$\displaystyle 2x+3=5x-3$
$\displaystyle x=2$
$\displaystyle AE=2(2)+3=7$
$\displaystyle AC=2(AE)=2(7)=14$
(6) The opposite angles of a parallelogram are congruent.
$\displaystyle 2x=120$
$\displaystyle x=60$
$\displaystyle 3y=60$
$\displaystyle y=20$