How many votes does the senate need to override a veto?

Me with this psychology homework, i’m struggling with it.

Alexander stephens’ opinion on secession and compromise led to what being written? a)the kansas-nebraska act b)the missouri compromise c)the u.s. constitution d)the georgia platform

Which of the following  bestillustrates a negative reinforcer?               a.  copland gives up candy to stave off chronic acid indigestion.    b.  nancy learns that she prefers chocolate over vanilla.    c.  carmine changes his major to english lit after failing a math exam.    d.  on a hot day, lindberg always drinks lemonade.