Current Electricity

In a potentiometer experiement, when three cells \(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) are connected in series, the balancing length is found to be \(420 \mathrm{~cm}\). If cells \(\mathrm{A}\) and \(\mathrm{B}\) are connected in series the balancing length is \(220 \mathrm{~cm}\) and for cells \(\mathrm{B}\) and \(\mathrm{C}\) connected in series in balancing length is \(320 \mathrm{~cm}\). The emf of cells \(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) are respectively in the ratio of