9^3 x 8 is the answer I believe
To tell if an equation has infinite solutions, the equation will be equal to each other.
For example,
x = x
x + 1 = x + 1
x - y = x - y
And so on...
And in special cases,
0x = 0
0x = 0(y + 1)
They have infinite solutions because there's no constant to determine the variable.
It is 1 because a penny is worth 1 cent.
This looks like the additive inverse property, because when you add something to its negative counterpart (or its additive inverse), you get 0 as a sum.
Another example would be 2+ (-2) = 0. -2 is the additive inverse for 2.