It's a linear equation in 'x'. The solution to the equation is the number
that 'x' must be in order to make the equation a true statement.
Fortunately, the equation is about as simple as it can be, so finding
the solution is really easy.
-x = -3 + 2
First, clean up the right side.
Combine the -3 and the +2: -x = -1
Multiply each side by -1: x = 1