dont get confused by the terms...here by transmission rate means the throughput of system= datasize / total time
100 / (TT+ 2PT)
TT=data size / bandwidth
= 100/ 100000= 1ms=0.001 sec
2PT=round trip time=2 sec
transmission rate= 100/(2+0.001) = 49.97 bps
this means even the bandwidth provided is 100000 bps, but we can transmit with the rate of 49.97 bps.