That answer your looking for is 80
9-5=4 Therefore f=4
Hope this helps
Answer: The volume of largest rectangular box is 4.5 units.
Step-by-step explanation:
Since we have given that
Volume = 
with subject to 
So, let 
So, Volume becomes,

Partially derivative wrt x and y we get that

By solving these two equations, we get that

So, 
So, Volume of largest rectangular box would be

Hence, the volume of largest rectangular box is 4.5 units.
3k-2=2k+4
-2k. -2k
k-2=4
+2. +2
k =6