Can someone please show me step by step how to solve this problem?

thanks in advance

People use their smartphones for applications that require an Internet connection. There are two types of connections used today: (i) either a data plan, where the user is paying the cellular provider a monthly fee for data, (ii) or, when a smartphone is within range of a WiFi network, the user may connect to this network and use WiFi. Assume that all packets that the user wants to download sit in a queue in a base station. When the user is using hist'her data plan, the transmission time of packets over the air is uniform in the interval [tcell -T.tceu Hz] with mean ta". When the user is using a WiFi connection, the transmission time is exponential with mean twi, and it is smaller than before since WiFi is faster than cellular data plans. The user requests packets according to a Poisson process ofrate A.