For simultaneous equations in variables \(x\) and \(y\), \(D_x = 49\), \(D_y = -63\), \(D = 7\), then find the value of \(x\).
Q.1 (B)(i) For simultaneous equations in variables \(x\) and \(y\), \(D_x = 49\), \(D_y = -63\), \(D = 7\), then find the value of \(x\).