According to the meaning of the question, ADE∽△ABC,

800 BC

∴△abc∽δade

The time is x ∴BD=2x.

AD = 8-2 times

AD/BD=DE/BC

(8-2x)/8=y/9

8y=72- 18x

y=(36-9x)/4

I hope it helps you! Give a good comment, thank you!