Answer is in the attachment below.
If O is the midpoint of NM that means that ON and OM are equal. And if OW=OM, then OW=OM=ON
Given that O is the midpoint of MN and OM = O W , we can prove that O W = ON by using the definition of midpoint and substitution of equal lengths. Since OM = ON as O is the midpoint, we arrive at the conclusion that O W = ON .
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