help solving this problem?

Let f(a) = 2x2 - 15x + 15 The slope of the tangent line to the graph of f (x) at the point (3, -12) is The equation of the tangent line to the graph of f(x) at (3, -12) is y = mx + b for m and b Hint: the slope is given by the derivative at x = 3, ie. f(3 + h) - f(3) lim h-0 h