area of playground= 9×15= 135m^2
area of lawn= 3×4=12m^2
total flooring area= 135-12= 123m^2
cost=36×123=$4428
Points of inflections are zeroes of the second derivative. We have:

So, the second derivative equals zero if and only if

So, this is the only point of inflection of this function.
I believe it is 68
Hope this is right!
Add e to both sides and subtract 2 from both sides :: v+f-2=e
Answer:
the answer is x=25 hope this helps