Answer:
Rotation then reflection
Step-by-step explanation:
The triangle starts where the light green one is. Then it is rotated 90 degrees clockwise around the point where the hypotenuse and longer leg meet. From the sark green triangle it is reflectd to where the purple triangle is.
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.
So 16=heads
18=tails
after you add some tails
18+x
ratio of heads to tails is 1:1.5
heads=16, didn't change
tails=18+x
so
1:1.5=16:18+x
fractionify
1/1.5=16/(18+x)
1/1.5=2/3
2/3=16/(18+x)
mutiply both sides by (3)(18+x)
2(18+x)=3(16)
36+2x=48
subtract 36 from both sides
2x=12
divide 2
x=6
6 tails added
total=heads+tails
heads=16
tails=18+6=24
total=16+24
total=40
6 tails added
40 total coins