Answer: x = 3
Explanation:
The question involves two triangles,
Big triangle AED,
small triangle ABC.
Both triangles are similar and
AED has base of 9 + 3 = 12 and heught of 12
ABC has base of 3 and height of x
To find x we equate the ratios of their height to their base
x/3 = 12/12
x/3 = 1
x = 3