Expanded Notation:
A. 654.362 = (6x100) + (5x10) + (4x1) + (3x0.1) + (6x0.01) + (2x0.001)
B. 125.384 = (1x100) + (2x10) + (5x1) + (3x0.1) + (4x0.01) + (8x0.001)
Answer:

Step-by-step explanation:
we know that
To find the inverse of a function, exchange variables x for y and y for x. Then clear the y-variable to get the inverse function.
we will proceed to verify each case to determine the solution of the problem
<u>case A)</u> 
Find the inverse of f(x)
Let
y=f(x)
Exchange variables x for y and y for x
Isolate the variable y


Let


therefore
f(x) and g(x) are inverse functions
<u>case B)</u> 
Find the inverse of f(x)
Let
y=f(x)
Exchange variables x for y and y for x
Isolate the variable y


Let


therefore
f(x) and g(x) are inverse functions
<u>case C)</u> ![f(x)=x^{5}, g(x)=\sqrt[5]{x}](https://tex.z-dn.net/?f=f%28x%29%3Dx%5E%7B5%7D%2C%20g%28x%29%3D%5Csqrt%5B5%5D%7Bx%7D)
Find the inverse of f(x)
Let
y=f(x)
Exchange variables x for y and y for x
Isolate the variable y
fifth root both members
![y=\sqrt[5]{x}](https://tex.z-dn.net/?f=y%3D%5Csqrt%5B5%5D%7Bx%7D)
Let

![f^{-1}(x)=\sqrt[5]{x}](https://tex.z-dn.net/?f=f%5E%7B-1%7D%28x%29%3D%5Csqrt%5B5%5D%7Bx%7D)
therefore
f(x) and g(x) are inverse functions
<u>case D)</u> 
Find the inverse of f(x)
Let
y=f(x)
Exchange variables x for y and y for x
Isolate the variable y





Let



therefore
f(x) and g(x) is not a pair of inverse functions
The answer is 21.
if u look at (7-2) that gives you 5 then 3x5 gives you 15 and then you add 15+6 to get your answer of 21.
The correct answer would be C. Hope that helps.