Hi, I am a newbie… can any kind soul help me with this?

3 Cells of 1.5V each are connected in series (two same polarity and one opposite polarity) , what is the effective potential difference across the terminal? Is it 1.5 V or 0 V? please help explain to me… Thanks

 

1.5 + 1.5 - 1.5 = ??????
(positive1.5 + positive1.5 + negative1.5)
Now, what do you think is the answer......1.5v or 0v ?