This is a very simple problem but I can't seem to get the correct answer for some reason.

Question:Find the slope of the function's graph at the given point.

h(t) =t^3 + 6t, (3, 45). Also. Find an equation for the line tangent to the graph there.

My answer is m=21 for the slope and for the equation of the tangent line, y=21x-54. Maybe I'm approaching the problem incorrectly?