1/3-1/9 , 10/21-1/3 ,14/15-3/5 пожалуйста помогите

1/3 - 1/9 = 3/9 - 1/9 = 2/910/21 - 1/3 = 10/21 - 7/21 = 3/21 = 1/714/15 - 3/5 = 14/15 - 9/15  = 5/15 = 1/3