Could anyone give me some pointers regarding this problem? Half-cell Xn+/X is connected with half-cell Yn+/Y and the potential difference is found to be 0.12V with Y being the positive electrode. Yn+/Y is connected with Cu2+ and the potential difference is found to be 0.13V with Cu being the positive electrode. If Cu2+ + 2 e- right arrow Cu is assigned the potential 0.34V versus the standard hydrogen electrode, what is the reduction potential of Xn+ + n e- right arrow X relative to the standard hydrogen half-cell? My tentative solution is 0.12 V + 0.13 V = 0.25 V. Does that look right? Thanks!