Respuesta :

59.99 - 59.99 x saving rate = 42.89

with saving rate = r%

59.99 - 59.99 x r% = 42.89

so 59,99 ( 1 - r%) = 42.89

1 - r% = 42.89 : 59.99

1 - r% = 0,7150

r% = 1 - 0,7150

r = 28,5%