a) 12/27 = k/9
k = (12 * 9) / 27 = 108 / 27 = 4
б) k/84 = 8/21
k = (8 * 84) / 21 = 672 / 21 = 32
в) 14/k = 98/35
k = (14 * 35) / 98 = 490 / 98 = 5
г) 14/15 = 122/k
k = (122 * 15) / 14 = 1830 / 14 = 915 / 7 = 130.714...
Ответ: а) k = 4; б) k = 32; в) k = 5; г) k = 915/7