Can anyone solve 4x^2 + 12x - 40 ? you would have to find what multiplies to get -40 but adds to get 12, but you do something with th 4x^2 as well

There's really nothing to solve, since there's no equation there.
Perhaps you want that expression factored.  We can do that.

First, all 3 terms share a common factor of 4.  Let's pull that out,
and see what's left to be factored:

                   4x² + 12x - 40  =  4 (x² + 3x - 10) .

Now, the expression left inside the parentheses looks
like it might be a lot easier to handle. 

Here's what the whole expression looks like after the
quadratic inside the parentheses is factored:

            4 (x² + 3x - 10)  =    4 (x + 5) (x - 2) .

There it is.  Understand ... we haven't changed anything,
and we haven't solved anything.  We only wrote the original
expression in a different form.  It's still just an expression that
stands for a number, and we won't know the number until
somebody tells us the value of 'x' .

The answer for your problem would be y-12