Because the two angles on the right add to 180 degrees, we can create this system:

We can also prove that

, which, when solved, shows that

.
When plugged in to the original equation, we find that y = 105 degrees.
Answer:
1680 kwhr
Step-by-step explanation:
See attached for explanation. I converted watt*hr to kW*hr by dividing by 1000.
Fans Bulbs
40 100
50 60 W
10 6 hours/day
20000 36000 W*hr/day
30 30 days/month
600000 1080000 W*hr/month
600 1080 kWhr/month
Total = 1680 kWhr/month
V = L * W * H
V = 4 * 4 * 8
V = 16 * 8
V = 128 cubic ft
The list is long, but here goes:
10/12, 15/18, 20/24, 25/30, 30/36, ... and so on.