Most important is what is the sequence number and how did you determine that?

Host A and B are communicating over a TCP connection, and Host B has already received from A all bytes up through to byte 280. Suppose Host A then send two segments to host B back-to-back. The first and second segments contain 120 and 150 bytes of data, respectively. In the first segment, the source port number is 503, and the destination port number is 80. Host B sends an acknowledgement whenever it receives a segment from host A. a) In the second segment sent from Host A to B, what are the sequence numbers, source port number, and the destination port number