The rate a which the surface area, S, decreases is

The surface area is
S = 4πr²
where r = the radius at time t.
Therefore

When r = 3 cm, obtain
![\frac{dr}{dt}]_{r=3} = - \frac{1}{3} \, cm/s](https://tex.z-dn.net/?f=%20%5Cfrac%7Bdr%7D%7Bdt%7D%5D_%7Br%3D3%7D%20%3D%20-%20%5Cfrac%7B1%7D%7B3%7D%20%5C%2C%20cm%2Fs%20%20)
Answer: -1/3 cm/s (or -0.333 cm/s)
First number is f
Second number is s
f-s=.7
f+s=1
Using elimination, you could solve this.
-1(f-s=.7); eliminate the first number.
-f+s= -.7
f+s=1
2s=.3
s=.15
Now find the second number by plugging it in:
.15+s=1
1-.15=.85
The numbers are .15 and .85.
A, D for pyramid and B, and C for prism
Answer: 3,885.71428571428571 I’m not sure
Step-by-step explanation: