How to calculate Ecell for the following electrochemical?

Multiplying the potentials by an integer when balancing half reactions is a common mistake. Potentials can only be switched from positive to negative and vise versa. This has to do with the definition of potential as Joules per unit of charge, so no matter how many charges there are the potential stays constant. .I am guessing that the answer is -1.5 V and that this cell is an electrolytic cell. The reaction is not spontaneous and only occurs if an outside source of 1.5 V is provided.