Quarter	1	2	3	4
2018	66	106	140	82
2019	73	119	165	91
2020	85	130	205	100

a)Use the technique of least squares method, to find the trend line b)Find the trend values c)Forecast the sales for 2021 second quarter. d)Plot the time series data and trend line. e)Using the same data in the table estimate the season variation component (S).