Sorry that this is a little late. All of these problems end up with the same process to get to the answer. Since you want to find the rate, you would want to divide the amount of time taken by itself to find the unit rate. So basically, 8. would be 20 cm in 24 hours. You would divide both by 24 and you get 20/24 cm in 1 hour. and then you simplify the fraction and boom, there's your answer.
