Please help me figure this out 15/4+(−4 1/3)?

Describe how to determine the average rate of change between x = 4 and x = 6 for the function f(x) = 2x^3 + 4. include the average rate of change in your answer.

Can you me with this question? i'll reward *30 points i just need with this one question so that i could solve the others. * edit: i originally set up the question to reward 30 points, but for some reason i can only reward 15. if you don't get 30, then i'm sorry. i'm still kind of new to this site

Whoever gets this right gets the ! the half life of a soul smelling substance is 4 years. if you have 8 oz of this strange substance, how much of it will you have after 20 years? show work.