Завдання 201 - 300 » 250

Обчисли: 1) 4/5 + 3/7 = (28 + 15)/35 = 43/35 = 18/35; 2) 5/12 + 9/20 = (25 + 27)/60 = 52/60 = 13/15; 3) 5/18 + 4/45 = (25 + 8)/90 = 33/90 = 11/30; 4) 12/17 + 27/34 = (24+27)/34 = 51/34 = 3/2 = 11/2 5) 5/9 – 7/18 = (10 - 7)/18 = 3/18 = 1/6; 6) 11/12 – 1/4 = (11 - 3)/12 = 8/12 = 2/3; 7) 8/21 – 4/35 = (40 - 12)/105 = 28/105 = 4/15; 8) 11/63 – 5/42 = (22 - 15)/126 = 7/126 = 1/18.