1) 105 = 3 * 5 * 7
924 = 2 * 2 * 3 * 7 * 11
2) НОК = 924 * 5 = 4620 НОД = 21
3) 105/924 = (3 * 5 * 7)/(2 * 2 * 3 * 7 * 11) = 5/(2 * 2 * 11) = 5/44
4) (2 * 44)/4620 - (5 * 5)/4620 = (88 - 25)/4620 = 63/4620 = (3 * 3 * 7)/(2 * 2 * 3 * 5 * 7 * 11) = 3/(2 * 2 * 5 * 11) = 3/220
5) 1. 5/18 + 7/12 = 31/36
2. 31/36 * 2 10/31 = 2
3. 4/17 - 20/51 = 8/51
4. 1 13/51 : 8 /51 = 8
5. 2 * 8 = 16