Respuesta :

If M is the midpoint of CD, CM = 2x+3 and MD = 3x-6, then:

MD = CM
3x - 6 = 
2x + 3
3x - 2x = 3 + 6
x = 9

CM = 2x+3 = 2*9+3  18+3 = 21
MD = CM = 21
CD = CM + MD = 21 + 21 = 42