Answer:
30 for walking, 15 for biking
Step-by-step explanation:
150 divided by 5
150 divided by 10
Answer:
5 seconds
Step-by-step explanation:
In 5 seconds it will be at 98 meters
x = -b/2a
x = -20/2(-2) = -20/-4 = 5
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.
<u>Let's solve this problem step-by-step</u>
<u>Let's set</u>:
2x + 6y = 36 -- equation 1
x + 4y = 20 -- equation 2
(equation 2) * 2
2x + 8y = 40 -- equation 3
(equation 3) - (equation 1)
2y = 4
y = 2 -- equation 4
Plug (equation 4)'s value of y into (equation 2)
x + 4(2) = 20
x = 20 - 8
x = 12
<u>Thus x = 12 and y = 2</u>
<u>Let's check, by substituting these values</u>

<u>Answer: x = 12 and y = 2</u>
Hope that helps!
Answer:
See below
Step-by-step explanation:
You know that he spent 1/3 of his earnings, and then 1/4. After this, he has $28.90. You can write the equation like this:
1/4(x * 1/3) = $28.90.
If you need to solve it:
1/4 * 1/3x = 28.90
1/12x = 28.90
x = 346.80