Provide an Appropriate Answer $w = x ^ { 2 } + y ^ { 2 } + 20 z + t$

Multiple Choice

Provide an appropriate answer.
-Suppose that $w = x ^ { 2 } + y ^ { 2 } + 20 z + t$ and $x + 4 z + t = 8$ . Assuming that the independent variables are $x$ , $y$ , and $z$ , find $\frac { \partial w } { \partial x }$ .

A) $\frac { \partial w } { \partial x } = 2 x - 5$
B) $\frac { \partial w } { \partial x } = 2 x + 5$
C) $\frac { \partial w } { \partial x } = 2 x + 1$
D) $\frac { \partial w } { \partial x } = 2 x - 1$