2021-005

Given that $\sin (xyz)=x+2z+y$, find the correct answer for the partial derivative of $z$ with respect to $y$, that is $\partial z/\partial y$.

1. $[1-yz\cos (xyz)]/[xy\cos (xyz)-2]$
2. $[1+yz\cos (xyz)]/[xy\cos (xyz)-2]$
3. $[1+xz\cos (xyz)]/[xy\cos (xyz)-2]$
4. $[1-xz\cos (xyz)]/[xy\cos (xyz)-2]$
5. none of the above

Original idea by: Soroor Salavati