Answer: D) 10
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Explanation:
I'm assuming points M and N are midpoints of segments FD and FE respectively. If that's the case, then segment DE is twice as long compared to segment MN. We consider MN to be a midsegment.
So,
DE = 2*(MN)
3x-2 = 2*(x+4)
3x-2 = 2x+8
3x-2x = 8+2
x = 10
