Answer:
[tex]\large\boxed{y=27}[/tex]
Step-by-step explanation:
Look at the picture.
ΔADC and ΔCDB are similar (AA). Therefore the sides are in proportion:
[tex]\dfrac{AD}{DC}=\dfrac{DC}{DB}[/tex]
We have:
[tex]AD=12,\ DC=18,\ DB=y[/tex]
Substitute:
[tex]\dfrac{12}{18}=\dfrac{18}{y}[/tex] cross multiply
[tex]12y=(18)(18)[/tex]
[tex]12y=324[/tex] divide both sides by 12
[tex]y=27[/tex]
