**Step-by-step explanation:**

Part A:

3.14(6*4+6*2)

I did this becuase i changed all of the r's to 6 and all of the s's to 4

Part B: 113.04

I got this because i first multiplied 6 by 4 and then multiplied 6 by 2 and added the answers. Then i multiplied the sum by 3.14

Critical points is where the derivative (slope) is zero or does not exist. So to do this we have to find the derivative of our function:

So we apply chain rule:

=

Set our first derivative to zero and solve for x:

3(x^2 - 1) * 2x = 0

So we can see that (by plugging in) 0, -1 and 1 makes our solution true

So our critical value is x = 0, x = -1, x = 1

A multi step equation always has a solution

12

The fractions already have the same denominator so you can just add

3/4+1/4 is 1

So 9+3=12

Hope this helps