(12 - x) * (5 - x) = 0

The equation is a product of two factors equal to zero. This means at least one of the factors must be zero.

1. Set the first factor to zero: 12 - x = 0, which gives x = 12.

2. Set the second factor to zero: 5 - x = 0, which gives x = 5.

The solutions are x = 12 and x = 5.