Answer:
To find f-¹(x) of f(x) equate f(x) to y
That's
f(x) = y
So we have

Next interchange the variables that's x becomes y and y becomes x
That's

Next make y the subject
Cross multiply
We have
4y - 7 = 10x
Move -7 to the right side of the equation
4y = 10x + 7
Divide both sides by 4
We have the final answer as

So

Hope this helps you
Re-written, I believe the equation is:
(W+23)+5=W+(23+5)
With this, the parenthesis have nothing multiplying into it, so we can drop the parenthesis to get:
W+23+5=W+23+5
Which is the same thing.
So I'd assume it is the Associative property, because you are combining the like terms of 23 and 5.
Hope this helps!
The formula of a function is the rise over run.
The slope would be 2/5.
Hope this helps!