A college student ingests 300 mg of caffeine at 6:00 am. He metabolizes the caffeine at 18% per hour. About how much caffeine is still in his system by 9:00 am?

The correct answer is 138 mg.

Step-by-step explanation:

To understand this problem we must first analyze it.

We know that the student's body metabolizes 18% of the caffeine ingested every hour.

Therefore we can solve that percentage to already have the number of metabolized caffeine per hour:

(300. 18): 100 =

5400: 100 = 54 mg

We now know that the student's body will metabolize 54 mg of caffeine per hour.

The question is much caffeine is still in his system by 9:00 am?

From 6:00 am to 9:00 am we have 3 hours of difference: 3 . 54 = 162

In three hours 162 mg of caffeine were already processed by his body, therefore, it still needs to be metabolized: 300 - 162 = 138 mg.

x = 17

step-by-step explanation:

1st step: isolate x.

24 - 3x = -27

-24         -24

-3x   =   -51

2nd step: divide.

-3x     =   -51

  3             3

  x       =     17

hope this