How to calculate the weight between neurons in ANN?
As far as I can tell, the information provided does not appear to be enough to answer your question, though I confess I am not familiar with what a "unipolar continuous threshold function" is, and it is not clear to me what $f(\text{net}_A$) represents nor what the loss function for this task is.  You might need to talk to your instructor or wherever you got that image from.  You might ask them what a "-" over an edge means.