DATA COMMUNICATIONS QUESTION - MULTIPLEXING

Suppose I have a multiplexer that is connected to a high-speed digital transmission system that can  transfer  1,536,000  information  bits per  second.  How  many  standard  voice  channels  is  the high-speed transmission system capable of carrying and how do you figure this out?  


What is the transmission efficiency of the High-Speed Digital Transmission System if the total number of bits traveling through the system is 1,544,000 bits per second? (Note that the extra bits are used  for overhead purposes such as synchronizing the multiplexer and demultiplexer).  Again, how do you figure this one out?