please Help me, I don't know how to do this question.

Question

In the illustration(in the link below) , suppose that DE ∥ BC. Find DE. (Assume BC = 10.)
DE = ?

www.webassign.net/ewenmath10/12-4-001-alt.gif

Answer 1

review properties of similar triangles.
why is ABC ~ ADE?
Now recall that that means
DE/BC = AD/AB

Answer 2

THese are similar triangles.
There sides are in proportion
6/DE = 12/10
Solve for DE : )

Answer 3

thank you guys