please help !
We know that ∆AEB is similar to ∆DEC.
Thus, AE and BE are proportional to DE and CE, respectively.
Since we know that the triangles are similar and that BE = 4 and CE = 2, we can infer that each side ∆AEB is twice as large as its counterpart in ∆DEC.
We know that AE = 7; therefore, its corresponding side, ED, must be half that length.
Therefore, ED = 3.5