Question

What is the inverse of the function f(x) = x +3?

Answer 1

Next time please add answer choices 

f(x) = y = x+3, Consider y=x+3. You just switch x and y:
 so y= x+3, becomes x=y+3. Once done, you isolate y:
x=y+3 or y = x-3. This this the inverse function of f(x)