Can anyone answer this trig question?

The displacement of a pendulum from rest can be represented by a cosine curve. The pendulum starts from a position 15 cm to the right of its rest position and swings 15 cm to the left of the rest position in 2 seconds. If, when you sketch the graph of the pendulum’s path, the vertical axis represents the displacement from the rest position and the horizontal axis represents time, write the function representing the motion in the form y = a cos [b(x+c)]+d.