Answer:
they are subtracting 6 from each number
Let
. The gradient of
at the point (1, 0, 0) is the normal vector to the surface, which is also orthogonal to the tangent plane at this point.
So the tangent plane has equation

Compute the gradient:

Evaluate the gradient at the given point:

Then the equation of the tangent plane is

The formula for this is: (sale price) / (1 - percentage)
Percentage have to be in decimal form, so divide percentage by 100 to get the decimal form.
220/(1-.20) = $275
The original price was $275.
40c=520
This is the proper equation because there are 40 quarters in $10. Thus, if we could only fit $10 worth of quarters in each wrapper, we can only fit 40quarters in each wrapper. C represents the amount of wrappers we will need.
Hope this helps!
Volume of a cube: V = s^3, where s is the length of the edge.
So, the sum of them will be 1^3 + 2^3 = 9