Ответ: 20 + (7 1/3 — 6 7/8) : 3/4 — (5 1/4 — 4 21/40) : 1 9/20 = 20 1/91) 7 1/3 — 6 7/8 = 22/3 — 55/8 = (8*22 — 3*55)/24 = (176 — 165)/24 = 11/242) 5 1/4 — 4 21/40 = 21/4 — 181/40 = (210 — 181)/40 = 29/403) 11/24 : 3/4 = 11/24 * 4/3 = 11/184) 29/40 : 1 9/20 = 29/40 : 29/20 = 29/40 * 20/29 = 1/25) 20 + 11/18 = 19 18/18 + 11/18 = 19 29/18 = 20 11/186) 20 11/18 — 1/2 = 371/18 — 1/2 = (371 — 9)/18 = 362/18 = 181/9 = 20 1/9