For each of the following cases, calculate the latency (from first bit sent to the last bit received). Assume the bandwidth of each link is 2 Gbps, and the size of each packet is 120 Kb (Kilo-bits). Note that little b is bit and big B is Byte. Assume the length of each link is 40 meters, and propagation speed is 2*106 meters per second. There is no queuing or processing delay. a. If the source sends a message containing 1 packet and there are 2 routers on the path. b. If the source sends a message containing 1 packet and there are 4 routers on the path. c. If the source sends a message containing 10 packets and there are 2 routers on the path. d. If the source sends a message containing 10 packets and there are 4 routers on the path.