Find the value of x that makes the shape a rhombus.

Given:
CDEF is a rhombus.
To find:
The value of x.
Solution:
We know that the diagonals of a rhombus are angle bisectors because they bisect each vertex angle.
[tex]5x+1=8x-20[/tex]
[tex]5x-8x=-1-20[/tex]
[tex]-3x=-21[/tex]
Divide both sides by -3.
[tex]x=\dfrac{-21}{-3}[/tex]
[tex]x=7[/tex]
Therefore, the value of x is 7.