An undiscovered planet many light years from earth has one

Question

Question: An undiscovered planet, many light years from Earth, has one moon in a periodic orbit. This moon takes 1310 x 10³ seconds (about 15 days) on average to complete one nearly circular revolution around the unnamed planet. If the distance from the center of the moon to the surface of the planet is 255.0 x 10⁶ m and the planet has a radius of 3.10 x 10⁶ m,

Part A: Calculate the moon's radial acceleration.

Please show how you obtained the answer.