P4. (5pts) Assume that a source sends a packet to the destination and there are 3 routers on the path. Assume the bandwidth of each link is 100 Mbps (Megabits/sec), and the size of each packet is 16 Kb (Kbits). Assume the length of each link is 20 km, and the propagation speed is 2 x 108 m/s. Assume each router processes a packet for 4 microseconds (dproc = 4 s). There is no queueing delay. Calculate the end-to-end delay to this packet (from first bit sent until the last bit received).