Y=5s+8a+200 is the right answer pretty sure
Think of it as two rectangular prisms next to each other, and find the volume of each one separately.
The big one on the left has a volume of 4 * 12 * 6, or 288.
The smaller one on the right has a volume of 2 * 6 * 6, or 72.
288 + 72 = 360. 360 cubic feet of water are needed.