8/14= 7/63= 30/84= 34*12/3*17= 9/20+1/15=

Найдем значения выражений:1) 8/14 = (2 * 4)/(2 * 7) = (1 * 4)/(1 * 7) = 4/7;2) 7/63 = 7/(7 * 9) = 1/(1 * 9) = 1/9;3) 30/84 = (15 * 2)/(2 * 42) = (15 * 1)/(1 * 42) = 15/42 = (5 * 3)/(14 * 3) = (5 * 1)/(14 * 1) = 5/14;4) (34 * 12)/(3 * 17) = (17 * 2 * 4 * 3)/(3 * 17) = (1 * 2 * 4 * 1)/(1 * 1) = 2 * 4 = 8;5) 9/20 + 1/15 = (9 * 3 + 1 * 4)/60 = (27 + 4)/60 = 31/60.