http://easycalculation.com/statistics/learn-correlation.php
based on those formulas, i created a table in excel that shows you what the data would look like applied to your problem.
that table is shown below:
x values y values x*y x^2 y^2
0 93 0 0 8649
1 90 90 1 8100
2 79 158 4 6241
3 66 198 9 4356
4 60 240 16 3600
5 56 280 25 3136
based on that data the important parameters have been calculated to be:
sum of x y x*y x^2 y^2
equals 15 444 966 55 34082
n >>> 6
slope = -8.228571429
y-intercept = 94.57142857
correlation = -0.983101215
regression equation is y = mx + b
m = slope and b = y-intercept
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these numbers should agree with what you derive using the online calculator taking into account rounding to a comparable number of digits to the right of the decimal point.
the mean of x is equal to 15/6 = 2.5
the mean of y is equal to 444/6 = 74