Respuesta :

n / (8/11) = (2 1/5) / (1 1/7) =
n / (8/11) = (11/5) / (8/7) =
cross multiply
(8/7)(n) = (8/11)(11/5)
8/7n = 8/5
n = 8/5 * 7/8
n = 56/40 which reduces to 7/5 or 1 2/5 <==
2  1/5 / 1 1/7  =  11/5 / 8/7 = 11/5 * 7/8  = 77 / 40

n / 8/11 = n * 11 /8 = 11n / 8  

11n / 8 = 77/40

55n/40 = 77/40

55n = 77
n = 77/55 = 7/5