Public Complex subtract (Complex subtrahend)

src/main/java/mandelbrot/Complex.java

@@ -126,7 +126,7 @@ public class Complex {
      * @return the complex number {@code (this - subtrahend)}
      */
     public Complex subtract(Complex subtrahend) {
-        return new Complex(this.imaginary - subtrahend.imaginary, this.real - subtrahend.real);
+        return new Complex(this.real - subtrahend.real, this.imaginary - subtrahend.imaginary);
     }
 
     /**