Given :(i) Cu+2 +2e-→Cu, E0 = 0.337V (ii)  Cu+2+e-→Cu+, E0 = 0.153V Electrode potential, E0 for the reaction,Cu+ + e-→Cu, will be

Electrodepotentials are intensive properties and can't be added. Converted into extensive properties  using Required equation is obtained by sutracting 2 from1 and simplifyingnE = n1E1 - n2E2