The half-reactions for a Daneill cell are given below:
Pb→ Pb2++ 2e– E°(ox) = +0.13 V
Cu2++ 2e– → Cu E°(red) = +0.34 V
Calculate E° for this cell.
Eocell = Eo ox + Eo red
Substitute and add. That's all there is to it.