Please help!!! I would like an explanation along with your answer. Thanks

Answer:
x = 12/13
BC = 140/13
Step-by-step explanation:
If A is the mipoint of BC, then AB is half of BC.
AB = BC / 2
8x − 2 = (3x + 8) / 2
16x − 4 = 3x + 8
13x = 12
x = 12/13
BC = 3x + 8
BC = 3 (12/13) + 8
BC = 36/13 + 104/13
BC = 140/13