A multiplexer $($MUX$)$ is a device that allows digital information from several sources

to be routed onto a single line for transmission over that line to a common destination.

Meanwhile, a demultiplexer $($DEMUX$)$ basically reverses the MUX function. It takes

digital information from one line and distributes it to a given number of output lines.

Design a $2-$to$-1$ MUX and $1-$to$-2$ DEMUX and combine them together to be one

communication line. Show your truth table and draw the logic circuits.