<h2>Answer</h2>
f(x) = 5(1.25)x + 4
<h2>Explanation</h2>
To solve this, we are going to use the standard exponential equation:
where
is the initial amount
is the growth rate in decimal form
is the time (in months for our case)
Since the hours of classic music remain constant, we just need to add them at the end. We know form our problem that Sue initially has 5 hours of pop, so 
; we also know that every month onward, the hours of pop music in her collection is 25% more than what she had the previous month, so 
. Now let's replace the values in our function:
Now we can add the hours of classical music to complete our function:
Going from 107 to 98 is (minus 9)
going from 98 to 90 is (minus 8)
going from 90 to 83 is (minus 7)
going from 83 to 77 is (minus 6)
following this pattern, the number after 77
is 77 minus 5 = 72
therefore your answer is 72
D. You multiply all measurements together. The thickness has nothing to do with how much air will be inside. (: hope this helped ya :)
