Respuesta :

B will be the answer for u
We can notice that in the two triangles,
1. two angles are equal and 
2. they share a common line(side).

This shows that the two triangles are similar. 
∴6.3/13.6 = 8.1/x

 6.3x = 8.1 × 13.6
         = 110.16

x =110.16/6.3
   = 17.4857

To the nearest tenth, 
Answer = 17.5