4/3 x 7=9.3333
4/3 x 8=10.666
Can't go over 10, so you can only make 7 batches.
Hope I've helped!
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

You need to find what 11% of 4 2/5 is.
You can convert 4 2/5 to 4.4 and 11% to .11
Then just multiply them together
4.4 * .11 = your answer