Packet A sends an IP packet of 180 bytes of data + 20 bytes of TCP header + 20 bytes of IP header to B.
IP layer of B now removes 20 bytes of IP header and has 200 bytes of data. So, it makes 3 IP packets - [80 + 20, 80 + 20 , 40 + 20] and sends to C as the Ip packet size of B is 100. So, C receives 260 bytes of data which includes 60 bytes of IP headers and 20 bytes of TCP header.
For data rate, we need to consider only the slowest part of the network as data will be getting accumulated at that sender (data rate till that slowest part, we need to add time if a faster part follows a slower part).
So, here 180 bytes of application data are transferred from A to C and this causes 260 bytes to be transferred from B to C.