а) (7/8) * 6/7 * 24 = (7 * 6 * 24) / (8 * 7) = 6 * 3 = 18
б) (3/4) * 7/16 * 7/1 = (3 * 7 * 7) / (4 * 16 * 1) = 147 / 64
в) 101/50 * 47/250 = (101 * 47) / (50 * 250) = 4747 / 12500
г) 9/4 * (10/13 * 15/26) = (9 * 10 * 15) / (4 * 13 * 26) = 1350 / 1352