Answer:
BC : BN = 8 : 3
Explanation:
Parallel lines divide any transversal into segments with the same ratio. That means ...
... BN : NC = AM : MD = 3 : 5
Since BC = BN + NC, the desired ratio is ...
... BC : BN = (BN+NC) : BN = (3+5) : 3
... BC : BN = 8 : 3