§ 5. Звичайні дроби » 1084

Обчисліть: 1) 811/21 – 215/21 + 2/21 = (7 – 2) + (32/21 – 15/21 + 2/21) = 5 + 19/21 = 519/21 2) 47/9 + 123/5 + 52/9 + 21/5 = (47/9 + 52/9) + (123/5 + 21/5) = 99/9 + 144/5 = 10 + 144/5 = 244/5 3) 218/15 – (37/15 + 108/15) = 218/15 – (3 + 10 + 7/15 + 8/15) = 218/15 – (13 + 15/15) = 218/15 – 14 = 78/15 4) (55/10 – 34/10) – (21/10 – 13/10) = 21/10 – (1 – 1 + 11/10 – 3/10) = 21/10 – 8/10 = 111/10 – 8/10 = 13/10