the answer would be ...
f(x) = -5/2x + 4
We know this because the constant in this equation, 4, is the y-intercept!
This means that the number without the variable is where the line intersects the y-axis.
Additionally, the slope is called the "rise over run", but in this case it is negative. At the point, 4, on the y-axis, we go down 5 units (the numerator of the slope) and to the right by 2 units (the denominator).
We find ourselves at where the line intercepts the x-axis!
I hope my explanation isn't confusing and that it is helpful! If you have any questions or concerns, message me! :)