The following are our company's annual sales ($ million) data from 2015 to 2021.Use the trend equation to forecast sales for 2025.

Year	2015	2016	2017	2018	2019	2020	2021
Sales $000,000	16	17	25	28	32	43	50

I saw one equation as follows: y = 2.3x - 6.1 is the trend equation for the given data. y=25.4 for x=10. A trend equation was discovered to be $y = (1.8)x + 13.9$ for the provided data. They can forecast revenues of $y = (1.8)(2025) + 13.9 = 100.1 million dollars in 2025 using this formula.

While another used: Utilizing the trend equation y = 5.75x + 7.1429

From y = mx + b

Where y = the Forecast sales for 2025

And x = time period

So Forecast = 5.75*Time Period + 7.1429

y = 5.75(2025) + 7.1429

y = 11491.0714 + 7.1429

y = 11498.21

1) how do you find the trend equation? where did the 5.75x and 7.1429 come from? What about 2.3x and 6.1? Which trend equation is correct?