Вправи для повторення розділу 1 » 29

Виконай дію: 1) 1/5 + 1/7 = (7 + 5)/35 = 12/35; 2) 5/12 + 1/16 = (20 + 3)/48 = 23/48; 3) 2/15 + 3/20 = (8 + 9)/60 = 17/60; 4) 1/12 + 5/18 = (3 + 10)/36 = 13/36; 5) 7/9 – 13/18 = (14 - 13)/18 = 1/18; 6) 4/5 – 3/8 = (32 - 15)/40 = 17/40; 7) 9/16 – 7/20 = (45 - 28)/80 = 17/80; 8) 7/12 – 2/9 = (21 - 8)/36 = 13/36;