Respuesta :

The triangles are similar, so the ratios of corresponding measures are equal.
.. x/(13 -x) = 2/3
.. 3x = 2(13 -x) . . . . "cross multiply"
.. 5x = 26 . . . . . . . . add 2x
.. x = 5.2 . . . . . . . . . divide by 5