Question

Which is the inverse of the function f(x)=1/3x+5 ?

Answer 1

The answer is b. y = 3(x-5)

To find inverse functions:

Swap x and y.
x = 1/3y + 5

Solve for y.
y = 3(x-5)

Answer 2

To find the inverse of a function, switch the x and the y and then solve for the new y.  Like this: $x= \frac{1}{3}y+5$.  Subtract 5 from both sides to get $x-5= \frac{1}{3}y$ and then multiply both sides by 3.  3(x - 5) = y.  B is your choice.