Charges 68 $\mu$ C, 61 $\mu$ C, and -15 $\mu$ C Are Brought from Infinity to the Respective Vertices of C

Short Answer

Charges 6.8 $\mu$ C, 6.1 $\mu$ C, and -1.5 $\mu$ C are brought from infinity to the respective vertices of an equilateral triangle with 11. cm sides.
(a) How much energy did it take to move the charges to the triangle vertices?
(b) What is the potential at the center of the triangle?