Calculation of potential.

Three point charges with values = 4.00 , = 3.00 , and = 5.00 are placed on three consecutive corners of a square whose side measures = 2.00 . Point A lies at the fourth corner of the square, diagonally across from. Point B lies at the center of the square. What are the values of the electric potential at point A and at point B? How much energy (supplied as work) is required to move a test charge = 2.00 from point A to point B? Assume the zero of electric potential is chosen to be at infinity.