Answer:
AD = 4.5
Step-by-step explanation:
Since DE is parallel to AC and intersects 2 sides of the triangle it divides those sides in proportion, that is
[tex]\frac{BD}{AD}[/tex] = [tex]\frac{BE}{EC}[/tex] , substitute values
[tex]\frac{3}{AD }[/tex] = [tex]\frac{8}{12}[/tex] ( cross- multiply )
8AD = 36 ( divide both sides by 8 )
AD = 4.5
