The maximum data transmission rate is the channel capacity C, according to Shannon's law: analog channel capacity C = Blb (1 + S/N) (unit: b/s)

B: channel bandwidth S/N: the average signal-to-noise ratio S: the signal power N: the noise power

Nyquist proposes that the ideal channel capacity (finite bandwidth, no noise) C = 2BlbM (unit: b/s)

M: number of states taken by the transmitted signal

So, C=2BlbM=2*6*lb8=36 (Mb/s). I hope you are still satisfied.