Fundamental frequency of a stretched sonometer wire is  $f_0$. When its tension is increased by 96% and length decreased by 35%, its fundamental frequency becomes  ${\eta }_1{f}_0$. When its tension is decreased by 36% and its length is increased by 30%, its fundamental frequency becomes  ${\eta }_2{f}_0$. The value of  $\frac{{\eta }_1}{{\eta }_2}$ is found to be  $\frac{7}{n}$. Find n.