1.5= 1 lap+ 0.5 lap = [2(85)+pi*(d)] + [85+pi*d/2]= 3[(85)+pi*d(1/2)]
just substitute d=74
In case you're not already aware, the expression 
is called the "difference quotient" and represents the average rate of change of a function 
over an interval ![[x,x+h]](https://tex.z-dn.net/?f=%5Bx%2Cx%2Bh%5D)
.
For the function 
, by substituting 
we get
Then the difference quotient is
where the last equality holds as long as 
.
18 is the answer im pretty sure if its wrong im sorry
The question reminds you of all the tools you need:
It says ...
"Opposite angles are equal."
So the upper right angle is x+40 just like the bottom left,
and the bottom right angle is 3x+20 just like the upper left.
And it says ...
"The sum of all angles is 360°."
You know what each of the four angles is, so you can addum all up,
set the sum equal to 360, find out what number ' x ' is, and then
use that to find the size of every angle.
Step b is wrong. The slope is the change in y over the change in x.
Step b should be (18- 8)/( 10-6)
= 10/4
= 5/2
