You're correct, the answer is C.
Given any function of the form

, then the derivative of y with respect to x (

) is written as:

In which

is any constant, this is called the power rule for differentiation.
For this example we have

, first lets get rid of the quotient and write the expression in the form

:

Now we can directly apply the rule stated at the beginning (in which

):

Note that whenever we differentiate a function, we simply "ignore" the constants (we take them out of the derivative).
10, 20w, 2w, and we are factors of 20w and 40wz
Answer:
The answer is simply 9x
Step-by-step explanation:
2x2=4-16+16x+80+0=2+7=9x