program that prints the result to linear equation of : ax+b = 0

Is it possible to write less for example by writing the conditions into one if- instruction or something like that.My point is to cut the source code and find a better way to sum the informations in the if instruction up.

import java.util.*; 
public class LinGlj4u {

    public static void main(String[] args) {        

        Scanner input = new Scanner(System.in);
        System.out.print("Bitte geben sie den Wert für a ein : ");
        double a = input.nextDouble();
        System.out.print("Bitte geben sie den Wert für b ein : ");
        double b = input.nextDouble();

        double rechnung;
        if (a + b > 0) {
            rechnung = -b / a;
            System.out.println(rechnung);
        } else if (a + b < 0) {
            rechnung = +b / a;
            System.out.println(rechnung);
        } else if (a + b == 0 || a - b == 0) {
            System.out.println("x = 0");
        }
    }
}