Given three numbers x, y, z, determine if one of them is the sum of the other two. If so, print the equation, otherwise print "None found". For example, if x = 2, y = 1, and z = 3, print "z = x + y". If there are multiple possibilities (such as all values equal to 0) favor the solutions in this order: "x = y + z", "y = x + z", and "z = x + y".