Respuesta :

[tex]Answer: \\ BE\parallel CD\Rightarrow \frac{AB}{BC} = \frac{AE}{ED} \\ \Leftrightarrow AE = \frac{AB \times ED }{BC} \\ \Leftrightarrow 7x - 40 = \frac{25 \times 18}{15} \\ \Leftrightarrow 7x - 40 = 30 \\\Leftrightarrow 7x = 70 \Leftrightarrow x = 10[/tex]

Answer: x=10

Step-by-step explanation:

By definition, if a line is parallel to one side of the triangle and intersects the other two sides in the samae ratio, then you can write the following ratio:

[tex]AB/BC=AE/ED[/tex]

 Now you must substitute values as followiing:

[tex]25/15=(7x-40)/18\\(25/15)*18=7x-40\\30+40=7x\\x=10[/tex]

Therefore, the answer is:

x=10