26) If a, b, c, and d are non-zero numbers such that c and d are solutions of x2+ ax + b = 0 and a and b are solutions of x2+ cx + d = 0, th

26) If a, b, c, and d are non-zero numbers such that c and d are solutions of x^2+ ax + b = 0 and a and b are solutions of x^2+ cx + d = 0, then a + b + c + d equals?