Equations of Line of Best Fit

A set of two variables are related non linearly can be converted to a linear equation.  The line of best fit can be written in the form
Y=mX+c

where
X and Y are in terms of x and/or y
m is the gradient,
c is the Y-intercept

Recall: To find equation of straight line

(1)  Equation of a straight line if gradient (m) and one points ( x 1 , y 1 )   are given:
Y y 1 =m(X x 1 )
(2)  Equation of a straight line if gradient (m) and y-intercept (c) are given:
Y=mX+c