Answer:
a. 
b. 
Step-by-step explanation:
First, we need tot find a general expression for the amount of caffeine remaining in the body after certain time. As the problem states that every hour x percent of caffeine leaves the body, we must substract that percentage from the initial quantity of caffeine, by each hour passing. That expression would be:

Then, to find the amount of caffeine metabolized per hour, we need to differentiate the previous equation. Following the differentiation rules we get:

The rate is negative as it represents the amount of caffeine leaving the body at certain time.
Answer:20.25
Step-by-step explanation:
If you do 81 divided by 4
I think Im not sure
80 km = 80000 m
5 saatte = 300 dk’dir
80000m/300 dk’dir = 266.666667 m/dk’dir
(Yazım yanlışsa kusura bakmayın türkçe bilmiyorum :) )
a^2 + b^2 = c^2
9^2 + 7^2 = get the answer then find the square root of it