а) 19/21 + 1/5 + 2/21 = (195 + 21 + 21)/105 = (95 + 21 + 2)/105 = 118/105 = 1 + 13/105 = 1 13/105.
б) (2/3 + 7/15) - 2/15 = (25 + 73)/15 - 2/15 = (10 + 21)/15 - 2/15 = 31/15 - 2/15 = 29/15.
в) 17/36 - (5/36 + 1/3) = 17/36 - (5/36 + 12/36) = 17/36 - 17/36 = 0.
а) 19/21 + 1/5 + 2/21 = (195 + 21 + 21)/105 = (95 + 21 + 2)/105 = 118/105 = 1 + 13/105 = 1 13/105.
б) (2/3 + 7/15) - 2/15 = (25 + 73)/15 - 2/15 = (10 + 21)/15 - 2/15 = 31/15 - 2/15 = 29/15.
в) 17/36 - (5/36 + 1/3) = 17/36 - (5/36 + 12/36) = 17/36 - 17/36 = 0.