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:
0.54
Step-by-step explanation:
You take 54 and divide it by 100
54/100 =0.54
Hope this helps!!
Answer:
x = 76.80°
4x - 142 = 165.18°
x/5 = 15.36°
5x/9 + 60 = 102.66°
Step-by-step explanation:
Total angle in a quadrilateral is 360
x + 4x - 142 + x/5 + (5/9)x + 60 = 360
259x/45 + - 82 = 360
259x/45 = 442
x = 76.7953668
x = 76.80°
4x - 142 = 165.18°
x/5 = 15.36°
5x/9 + 60 = 102.66°
The old photocopier can make x manuals in an hour. The new photocopier can make 4x. Combined, they made 5x manuals in an hour.
In one hour they can make 1/28 of the manuals.
1/(28*5)=1/140 is the rate.
The new photocopier can make all the manuals in 4/140 or 35 hours.
The old one can make them in 140 hours.