Circumference of a circle =

They are all multiplied by each other
r = radius
we know our radius is 40
and...

= 3.14
so we would use this expression 3.14 x 40 x 2 As a added bonus ill solve it for you :P
3.14 x 40 x 2 = 251.2
The circumference of this ice skating rink is 251.2 feet
6.000 - 4.000 = 2.000
It is a very simple equation. The easiest way to remember it would be to look at the first two numbers. 6 subtract 4 equals 2. So when you see this equation, simply for starters do 6 subtract 4, which equals 2, and then add a decimal place and the 3 zeros at the end. Does that make sense? Please let me know whether this was useful to you or not, and if you have any further questions please feel free to ask so on comments. Thank you!
27-2b > -6
-2b > -6-27
-2b > -33
b < -33/-2 (you have to change the sign when you divide with a negative number)
b < 16.5
(all the signs are supposed to have a line under them to make them greater or equal or less than or equal to)