Answer:
The diameter decreases at a rate of 0.053 cm/min.
Step-by-step explanation:
Surface area of an snowball
The surface area of an snowball has the following equation:

In which d is the diameter.
Implicit differentiation:
To solve this question, we differentiate the equation for the surface area implictly, in function of t. So

Surface area decreases at a rate of 3 cm2/min
This means that 
Tind the rate (in cm/min) at which the diameter decreases when the diameter is 9 cm.
This is
when
. So




The diameter decreases at a rate of 0.053 cm/min.
Answer:
Each pretzel is $4.99
Step-by-step explanation:
20 - 5.03 = 3x
14.97 = 3x
4.99 = x
I'm sorry, but I don't understand ;-;
X = pens and y = pencils
4x + 7y = 13.25
y = 0.75
4x + 7(0.75) = 13.25
4x + 5.25 = 13.25
4x = 13.25 - 5.25
4x = 8
x = 8/4
x = 2 <===so each pen cost 2 bucks