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

Step-by-step explanation:
AB = a
AP = 2PQ = 2QB
AB = AP + PQ + QB
= AP +
+ 
AB = 2AP
AP =
-----(1)
And we know QB = 
QB= AP/2 =
---------(2)
Now midpoint of AP =
×
= 
and midpoint of QB =
×
= 
distance between these midpoints =
- 
= 
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