1) 1/12 * 5 5/11 + 11/30 * 5 5/11 - 7/18 * 5 5/11 = 1/12 * 60/55 + 11/30 * 60/55 - 7/18 * 60/55 = 1/11 + 2/5 - 70/165 = 27/55 - 70/165 = 81 - 70 / 165 = 11/165 = 1/15
2) 1/14 * 1 4/11 + 8/21 * 1 4/11 - 3/35 * 1 4/11 = 1/14 * 15/11 + 8/21 * 15/11 - 3/35 * 15/11 = 15/154 + 120/231 - 9/77 = 45 + 240 / 462 - 9/77 = 285/462 - 9/77 = 95/154 - 9/77 = 95 - 18 /154 = 77/154 = 1/2