Answer:
C) x = 20
Explanation:
Since ABCD is a rhombus, we know that the diagonals of ABCD bisect each other at right angles.
This means that:
m ∠ AED = 90°
We are also given that m∠AED = 5x – 10.
Setting these two equations equal to each other, we get:
5x - 10 = 90
Add 10 on both sides:
5x - 10 + 10= 90 + 10
5x = 100
Divide both sides by 5.

x = 20
Therefore, the value of x is 20.