Answer:
y = - x + 13
Step-by-step explanation:
The equation of a line in slope- intercept form is
y = mx + b ( m is the slope and b the y- intercept )
Here m = - 1, thus
y = - x + b ← is the partial equation
To find b substitute (9, 4) into the partial equation
4 = - 9 + b ⇒ b = 4 + 9 = 13
y = - x + 13 ← equation of line
