20+(7 1/3-6 7/8): 3/4-(5 1/4-4 21/40): 1 9/20=? решите .

20 + (7 1/3 - 6 7/8) : 3/4 - (5 1/4 - 4 21/40) : 1 9/20 = 20 1/9
1) 7 1/3 - 6 7/8 = 22/3 - 55/8 = (8*22 - 3*55)/24 = (176 - 165)/24 = 11/24
2) 5 1/4 - 4 21/40 = 21/4 - 181/40 = (210 - 181)/40 = 29/40
3) 11/24 : 3/4 = 11/24 * 4/3 = 11/18
4) 29/40 : 1 9/20 = 29/40 : 29/20 = 29/40 * 20/29 = 1/2
5) 20 + 11/18 = 19 18/18 + 11/18 = 19 29/18 = 20 11/18
6) 20 11/18 - 1/2 = 371/18 - 1/2 = (371 - 9)/18 = 362/18 = 181/9 = 20 1/9