Answer:

Step-by-step explanation:
The given function is
f(x) = 4x
As we know
f(x) = y, which implies x= 
Therefore,
y = 4x
x = 
as x= 
So,

replacing y by x in the above expression

So our inverse function is 
Answer:
what?
Step-by-step explanation:
I DONT KNOW FHUEITHNGIFJTFRJNRGV
H
Answer:
$21
Step-by-step explanation:
starting money: 51
cost of each book = 3
total books bought = 10
3*10 = $30 spent on books
51-30 = $21 left