The answer is 216 cubic feet. How? All you have to do is multiply every number then divide it by 2. Like this: 2*12*18=432. 432/2= 216 cubic feet.
Two equations with infinite solutions would look the exact same. Example:
y=mx+b
y=mx+b
Example 2
y=2x+5
y=2x+5
For an equation with no solution they would have the same slope but different y intercepts. An equation with same slope and same y intercepts would have infinite solutions.
4/5=0.8
1/50=0.02
Hope that helps