We are transferring 256 bytes long frames from the sender to the receiver by way of a 28,8 kbps modem line. Each time, having sent the frame, we wait for an acknowledgement of one byte´s length. Calculate the additional time required by this compared to the situation that no acknowledgements are sent. We assume that there are no errors so that no frames have to be resent. The propagation velocity of the transmission is 2× 108 m/s, the distance between the sender and the receiver is 20 km and the handling time of the frame by the receiver is 5 ms starting from the moment the entire frame has been received.