C. 15
-1 is not a natural number so B is not your answer
0.5 is not a whole number so D is not your answer
0 is not a natural number so A is not your answer
The answer of
<span>-45+(-30)-90= -165
Hope this helps <3
</span>
Given a polynomial
and a point
, we have that

We know that our cubic function is zero at -4, 0 and 5, which means that our polynomial is a multiple of

Since this is already a cubic polynomial (it's the product of 3 polynomials with degree one), we can only adjust a multiplicative factor: our function must be

To fix the correct value for a, we impose
:

And so we must impose

So, the function we're looking for is

Okay this is how I would figure this out:
I would take 9 divided by 3 and get 3, so he can tile abut 3 square ft. in 15 minutes.
Then, I would multiply 3 by 4 because there are 4 15 in an hour. I would get 12.
So it takes Jakob 1 hour to tile 12 square feet.
Your answer is: He can tile about 12 square feet per hour.
Hope this helped :)