Solve the all parts of given problem:
Problem: Two point charges are on the y-axis. A 2.5 µC charge is located at y = 1.35 cm, and a -2.18 µC charge is located at y = -1.50 cm.
Part A: Find the total electric potential at the origin.
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Part B: Find the total electric potential at the point having coordinates (1.50 cm, 0).
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Show how you get the answer, so that I can better understand how to do it.