5/14 < 8/21, так как 15/42 < 16/42
14 = 2 * 7 21 = 3 * 7 НОК (14; 21) = 2 * 3 * 7 = 42
42 : 14 = 3 42 : 21 = 2
31/88 < 25/66, так как 93/264 < 100/264
88 = 2 * 2 * 2 * 11 66 = 2 * 3 * 11 НОК (88; 66) = 2 * 2 * 2 * 3 * 11 = 264
264 : 88 = 3 264 : 66 = 4