from Equilibrium,clockwise moment=anticlockwise moment\\\\(W \ imes 15 = 75 \ imes g \ imes 25\\\\)\\\\(m \ imes g \ imes 15 = 75 \ imes g \ imes 25 \\\\)\\\\(\ herefore = \\cfrac{ 75 \ imes 25 }{ 15 }=125 g\\\\)