Here's the question you clicked on:
fra1234
An object moves along the graph of y = f(x). At a certain point, the slope of the curve is 1/2 and the x coordinate of the object is decreasing at the rate of 3 units per second. At that point, how fast is the y-coordinate of the object changing? This is the problem. What is that 1/2? Isn't it the rate of change of Y, since it is the slope at that point? How would you solve it?
The tangent at that particular point has gradient 1/2. It's the rate of change of y with respect to x, at that particular point. f'(x)=1/2 at that point.