y = -
x + 3
the equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y-interceot )
to calculate m use the gradient formula
m = (y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁ ) = (0, 3) and (x₂, y₂ ) = (4, 0 ) ← 2 points on line
m =
= -

the line crosses the y- axis at (0, 3 ) → c = 3
y = -
x + 3 ← in slope-intercept form