An equation that models the amount of storage left as a function of the number of songs is
y = -0.004x + 16.024
How to write the equation
The equation graphed is written in the slope intercept form s below
y = mx + c
where
m = slope
x = intercept
The equation is modelled using a graphing calculator, the the equation of the regression line is
y = -0.004x + 16.024