Answer:
y = - x + 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 ) = (9, 0) ← 2 points on the line
m =
=
= - 1
The line crosses the y- axis at (0, 9 ) ⇒ c = 9
y = - x + 9 ← equation of line