Question

Given f(x) = the quantity of x minus 7, divided by 3, solve for f−1(4).

Answer 1

f(x) = (x - 7)/3.  

For inverse function, switch the x and y values and then solve for y. 

y = (x - 7)/3 ..... this is still the original function 
x = (y - 7)/3 ...... I switched the x and y 
3x = y - 7 
y = 3x + 7 .... this is the inverse 
f⁻¹(x) = 3x + 7 
f⁻¹(4) = 3(4) + 7 = 19 ... 19 is your final answer!

19

Hope this helps :)

Answer 2

Solution:

f(x)=$\frac{x-7}{3}$

Or , y = $\frac{x-7}{3}$

→ 3 y = x-7

→ x = 3 y +7-----(1)

Now replace x by y in equation 1 ,to get the inverse of f(x)

$f^{-1}(x)= 3 x + 7$

$f^{-1}(4)= 3 \times 4 +7=19$