answer: y = 3x - 27
Step-by-step explanation:
equation of a straight line: y = mx + c
( m is the slope and c the y- intercept )
here m = 3 , then y = 3x + c ← is the partial equation
to find c substitute (6, - 9) into the partial equation
-9 = 18 + c ⇒ c = -9 - 18 = - 27
y = 3x - 27 ← equation of line