Respuesta :

Given that the triangles are equal then the ratio of similar sides are equal

(x + 3)/15 = x/(15 - 6)

(x + 3)/15 = x/9

Cross multiply

15x = 9(x + 3)

Expand

15x = 9x + 27

Collect like terms

15x - 9x = 27

6x = 27

Divide both sides by 6

x = 27/6

= 9/2

= 4.5