9514 1404 393
Answer:
x = -9
Explanation:
Segment NL is twice the length of midsegment WV.
2WV = NL
2(x+15) = x+21
2x +30 = x +21 . . . . simplify
x = -9 . . . . . . . . . . . . add -30-x
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Additional comment
This value of x means the other segments are ...
MN = 12
WV = 6
NL = 12