Thank you for the opportunity to help you with your question! the solution is as such:

The avg rate of change of such function is :

Slope of the secant

I.e slope of the line with points (a, f(a)) and (b, f(b))

So here the avg rate is [f(c) - f(a)] / (c-a)

Please let me know if you need any clarification. I'm always happy to answer your questions.awaiting a positive feedback. It was lovely helping you. Looking forward to help you again. A positive feedback awaited thank you.