Задача D

SolveLinearEquations.java

private static void SolveLinearEquations(int a, int b, int c, int d, int e, int f) {

        float D = a * d - c * b;
        float Dx = e * d - f * b;
        float Dy = a * f - c * e;

        if (D != 0) {
            // решение единственное
            float x = Dx / D;
            float y = Dy / D;
            System.out.print(2 + " ");
            System.out.printf("%.2f", x);
            System.out.print(" ");
            System.out.printf("%.2f", y);
        } else {
            if (Math.abs(a) + Math.abs(b) + Math.abs(c) + Math.abs(d) == 0)
                if (Math.abs(e) + Math.abs(f) == 0) {
                    // любая пара
                    System.out.println("2XY");
                } else {
                    // решений нет
                    System.out.println(0);
                }
            else {
                if (Dx != 0 || Dy != 0) {
                    System.out.println(0);
                } else if (b == 0) {
                    System.out.print("1Y ");
                    System.out.printf("%.2f", (float) e / a);
                } else if (a == 0) {
                    System.out.print("1X ");
                    System.out.printf("%.2f", (float) e / b);
                } else
                    System.out.println(1);
            }
        }
    }