During the discharge of a lead storage battery, the density of H₂SO₄ fell from 1.225 gm/ml to 0.98 gm/ml. $H_{2}S{O}_4$ of density 1.225 gm/ml is 40% by weight and that of density 0.98 gm/ml is 20% by weight. The number of ampere hours for which the battery is used containing 1 L of the acid is 16.08 x. Calculate the value of x. 
(volume remains constant during the process)