the functional equation of the line is f (x)=a*x+b you have already a: -4 -->f (x)=-4 x+b Now you can use the point (3;-3) 3 is the x-coordinate and -3 the f (x)-coordinate --> -3 = -4*(3) + b Now you can solve it -3 = -12+b (+12) b = 9 ANSWER: f (x) = -4x + 9
