The frequencies of three tuning forks $\mathrm{A}, \mathrm{B} and \mathrm{C} are related as \mathrm{n}_{\mathrm{A}}>\mathrm{n}_{\mathrm{B}}>\mathrm{n}_{\mathrm{C}}. When the forks \mathrm{A} and \mathrm{B} are sounded together, the number of beats produced per second is 'n_1'. When forks \mathrm{A} and \mathrm{C} are sounded together the number of beats produced per second is 'n_2'. How may beats are produced per second when forks \mathrm{B} and \mathrm{C}$ are sounded together?