Stuck by a transport layer (networking) question

Solution for Stuck by a transport layer (networking) question
is Given Below:

I am trying to learn some computer networking knowledge and I am stuck on this particular question, if anyone can give some advice or something I’ll be very grateful, thank you!

Here’s the question:

Based on the image: if the payload of the segment sent from Host B to Host A is 100 bytes and it is received successfully, what will be the sequence number value sent in the next segment from Host A to Host B?

B ACK’d 103, so that is the next SEQ B expects to receive, but that might already be en-route, or this ACK could be lost en route, so you cannot say for sure what SEQ will be actually be sent from A next. The # of bytes sent from B does not matter for this question (a red herring). Also note that these are only the bytes in the TCP payload, not all the bytes in the packet/frame.

ACK value help enable ordered, reliable data transfer. The ACK value, say x, sent by the receiving host indicates that it has received cumulated data till value x and is expecting the next segment to carry a SEQ number of x.

According to the image, host B ACK’d with 103, indicating that the sequence number of the next packet/segment it is expecting to receive is 103. Hence, Host A should send SEQ = 103 to Host B.