5.15 for the first hour after subtracting 12.20(7.15)
#1 There is no area of a cube. There is only a volume.
#2 The formula is

where s is the side.
Substitute 729 in V since that is the volume.

Take the cube root and you will get
9.
So the formula is
and the side is 9.
13. Answer: n ≥ 108
<u>Step-by-step explanation:</u>
18 ≤ n ÷ 6
<u>×6 </u> <u> ×6 </u>
108 ≤ n → n ≥ 108
Note: The line under the inequality symbol represents a closed dot
Graph: 108 ·---------------→
************************************************************************************
14. Answer: x > -4
<u>Step-by-step explanation:</u>
-3x < 12
<u>÷(-3) </u> <u>÷(-3) </u>
x > -4 <em>Flip the inequality sign when × or ÷ by a negative </em>
Note: No line under the inequality symbol represents an open dot
Graph: -4 o-----------→
I apologise, but it is as though that there is some missing necessary information. Perhaps there was an error?