As you have seen, a central focus of debate on China–United States relations concerns the economy. Here there are strong arguments and historical evidence that each nation reaps substantial benefits (for example, in terms of burgeoning trade between the two countries). Many therefore see this aspect of the relationship as positive-sum where large absolute gains are available. If this is so, then it creates an important basis for both states to foster cooperative relations in the future.
However, it is worth noting that even here, there is much to disentangle. Although the estimation of costs and benefits of different courses of action is important, and governments do often try to evaluate the economic benefits they can get from a particular relationship or trade deal in monetary terms, it is never an exact science. Moreover, there may be a divergence between the benefits to the economy as a whole and the costs and benefits to particular groups within that economy. For example, rising imports from China are popularly seen in the West as a zero-sum ‘problem’ (benefitting China, harming Western economies), especially by those sectors which compete directly against those imports. It is claimed they lead to relocation or closure of domestic business and the loss of jobs. Yet, for the Western capitalist economies as a whole, these costs are countered by the benefits to domestic consumers of cheap imports and the overall boost to world economic growth that China and other Asian economies have provided. Both of these have made a significant contribution to maintaining Western standards of living while also benefitting China, strengthening the view that this is a win–win relationship. In real political debates as well as in the analysis within international relations, these are competing claims that you need to be able to work through carefully in arriving at your own assessment.