Answer:
y = - 2x + 9
Explanation:
The equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y- intercept )
Calculate m using the slope formula
m =

with (x₁, y₁ ) = (0, 9) and (x₂, y₂ ) = (4, 1) ← 2 points on the line
m =
=
= - 2
The line crosses the y- axis at (0, 9 ) ⇒ c = 9
y = - 2x + 9 ← equation of line