31. I'm not positive but give it a shot if it is wrong message me back!
Hope you can see my workout in the picture I attached below.
f⁻¹(x) =

AND
f⁻¹(19) =
Answer:
Slope: 1
Y-intercept: (0,3)
Step-by-step explanation:
The y intercept is when the slope reaches the y-axis line. In this case, it is given to us. Anything that is formed like this: (0, y) is the y-intercept.
Y intercept: (0, 3)
For slope, you can use the formula rise over run. 
From the picture, I have drawn the rise over run, which is
, which is also 1.
Slope: 1
Hope this helped.