Parasitism is when one is benefiting while the other is being harmed; commensalism is when one is benefiting and the other isn’t affected; and mutualism is basically in its name, they’re both mutually benefiting.
Base on your question where a concentration cell consist of two SN/SN2+half cells. The solution in one half cell A is 0.13M SN(NO3)2 and is 0.87 M Sn(NO3)2 in the other half cell to get the cell potential at 25 degree the answer is 0.059/2 log0.13/0.87
