ok some questions for you.
What is the wavelength? (distance from crest to crest)
What is the amplitude?
What is the midline?
If there was no dislacement the crest of cosx is on the y axis. But it is moved a little bit in the negative direction.
So how far has it moved. I means what is the x value of the crest?
Answer these questions and then I will help you finish it.