Answer:

Step-by-step explanation:
The given equation is 
Differentiate both sides with respect to x

Take y and 1 to other sides of the equation

Factor out dy/dx from the left hand side of the equation

Divide both sides by (x+1)

Independent because what you get in the first one doesn't effect the second
Answer:
function
Step-by-step explanation: A function is the one where you put an input to find x or y
Answer:
$100
Step-by-step explanation:
40x30=1200
1200/12=100