Label the 3 distinct sides of the box. I arbitrarily chose the letters a, b and c. Use the info about areas as follows:
ab=54 in^2 ac=90 in^2 bc=60 in^2
Here you have 3 equations in 3 unknowns (a, b and c), which is enough info to use to determine a, b and c. Then the volume of the box is a*b*c.
Example: bc = 90, but c = 60/b. You could subst. 60/b for c in the 2nd and 3rd equation, which will eliminate c completely and leave you with 2 equations in 2 unknowns.
Continuing this procedure, I determined that a=9, b=6 and c=10. Thus, the volume of the box is V = 9*6*10 = 540 cubic inches (answer)
Since the initial fee is $90, you will subtract $90 from $330, getting $240. Since every hour after 1 hour is $60, you would divide $240 by $60 getting 4 hours
