Respuesta :

DEF = BAC : x = 15 <==

once u allign ur triangles, u will see that there is a scale factor of 1.5.
6 * 1.5 = 9

1.5(x - 5) = 15
1.5x - 7.5 = 15
1.5x = 15 + 7.5
1.5x = 22.5
x = 22.5/1.5
x = 15 <==