Total production costs for the wheelbarrow department of Greene Garden Products over a year are in the table below.

Month	Units Produced	Production cost
Jan	2,000	100,000
Feb	3,400	139,400
Mar	1,600	78,400
Apr	3,200	150,400
May	2,900	145,000
Jun	2,800	117,600
Jul	1,800	86,400
Aug	3,000	150,000
Sep	2,700	118,800
Oct	3,500	161,000
Nov	2,900	121,800
Dec	2,300	108,100

Use high-low analysis to derive a formula to estimate production costs. (2 marks)