Answer:
I don't think you are doing anything wrong. Just ignore it and write the repeating decimal. If you're asked to do it, round it up instead.
180
Because 120 divided by 2 is 60.
And 120 + 60 is 180
Just add the displacement value to variable. If this value is positive, the graph will move to the right, otherwise it will shift to left.
Where: x=displacement value
If you notice any mistake in my English, please let me know, because I am not native.