Respuesta :

The rule for secants tells you
  EC·ED = EB·EA
  (x+4)(x+5) = (x+1)(x+12)
  9x+20 = 13x+12 . . . . . . simplify, subtract x²
  8 = 4x . . . . . . . . . . . . . . add -12-9x
  2 = x

The value of x is 2.