The original air present after 8 breaths will be equal to 179.81 ml.
<h3>What is an equation?</h3>
The equation in mathematics is the relationship between the variables and the number and establishes the relationship between the two or more variables.
It is given in the question that:-
During normal breathing, about 12% of the air in the lungs is replaced after one breath
If the initial amount of air in the lungs is 500 mL
how much of the original air is present after 8 breaths?
The calculation for the eduction of the air will be done by the following equation:-

=179.88 ml
Hence original air present after 8 breaths will be equal to 179.81 ml.
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Answer:
x=12.50
y = 17.50
Step-by-step explanation:
x = Amount of one Derek withdrawal
then amount of John withdrawal =x+5
Total withdrawals of Derek = no of times x one time withdrawal
= 7(x) = 7x ... i
No of John withdrawal = no of times x one time withdrawal
= 5(x+5) ... ii
Given that i and ii are equal
i.e. 7x =5(x+5)
7x = 5x+25
2x =25
x = 12.50 dollars
Y = 17.50 dollars
Checking part:
total derek withdrawal = 7(12.5) =87.50
Joh's withdrawal = 5(17.50) = 87.50
Since both are equal, our answers are right.
Solution: Derek withdrew each time 12.50 dollars each for 7 times and John withdrew 17.50 dollars each for 5 times.
Answer:
25 miles per hour
Step-by-step explanation:
Given



The joint variation can be represented as:

Where:

Required
Find V, when: 
We have:

Express as an equation

Where k is the constant of variation
Make k the subject

When: 
We have:



When: 
We have:

Substitute:
and 

Make V the subject



It is -5/8x (the slash represents a fraction sign)
Answer:
5x +11
Step-by-step explanation: