Answer:
$30
Step-by-step explanation:
To find the cost, plug in 10 for x, then simplify
1.5x + 15
1.5(10) + 15
= 30
So, it will cost Johnny $30 to download 10 songs
Given:


To find:
Whether f(x) and g(x) are inverse of each other by using that f(g(x)) = x and g(f(x)) = x.
Solution:
We know that, two function are inverse of each other if:
and 
We have,


Now,
![[\because g(x)=\dfrac{8}{x}]](https://tex.z-dn.net/?f=%5B%5Cbecause%20g%28x%29%3D%5Cdfrac%7B8%7D%7Bx%7D%5D)
![[\because f(x)=\dfrac{8}{x}]](https://tex.z-dn.net/?f=%5B%5Cbecause%20f%28x%29%3D%5Cdfrac%7B8%7D%7Bx%7D%5D)


Similarly,
![[\because f(x)=\dfrac{8}{x}]](https://tex.z-dn.net/?f=%5B%5Cbecause%20f%28x%29%3D%5Cdfrac%7B8%7D%7Bx%7D%5D)
![[\because g(x)=\dfrac{8}{x}]](https://tex.z-dn.net/?f=%5B%5Cbecause%20g%28x%29%3D%5Cdfrac%7B8%7D%7Bx%7D%5D)


Since,
and
, therefore, f(x) and g(x) are inverse of each other.