Question 705653
There are two lines AC and DF
B is midpoint in AC => AB = BC  -> Eq 1
E is midpoint in DF => DE = EF  -> Eq 2
Given that AB = EF -> Eq 3
Multiply Eq 3 by 2
=>2*AB = 2*EF
Hence 2AB = 2EF   -> Eq 4

Since B is midpoint in line AC, 2AB = AC
Since E is midpont in line DF, 2EF = DF 
Hence AC = DF
i.e., line AC = line DF