How do you find the rate of change?

First derivative will give the rate of change of a function

How much one quantity change in relation to another

Rate of change is a value we can find on a graph. It is simply how quickly the y component changes relative to the x component. To work this out between points (x1,y1) and (x2, y2), we can divide the change in 2 y values by the change in 2 corresponding x values as such -> (y2 - y1)/(x2-x1)

Work out the gradient, which you do by finding the change in y over the change in x.

The rate of change in the most simple terms is the "change in something" divided by "the time it took to change". In GCSE maths this often comes up with speed and time graphs. If they ask you to find the rate of change at a certain time from a graph you first draw a tangent to the graph at that point then work out the gradient of that tangent. The gradient on a speed(velocity) - time graph is the rate of chenge of speed(velocity).