Answer:
The answer is "$80".
Step-by-step explanation:
Please see the attached file for the whole question.
Yolanda's total pay y changes for each 'English is fun' sold x, i.e.
[tex]\frac{\delta y}{\delta x} = \frac{dy}{dx} \\\\y = 1900+80 x[/tex]
separating the above equation:
[tex]\frac{dy}{dx}= 80[/tex]
Therefore,
[tex]\frac{dy}{dx} = \$80[/tex]
For each 'English is enjoyable' sold x, the change in Yolanda total compensation y is [tex]\$80[/tex].
