а) 9/10 * 5/12 = 9/24 = 3/8
б) 3/5 : 11/5 = 3/5 * 5/11 = 3/11
в) 21/22 * 2/5 = 21/55
г) 7/8 : 7/16 = 7/8 * 16/7 = 16/8 = 2
д) 1 3/5 * 2 1/2 = 8/5 * 5/2 = 8/2 = 4
е) 1 3/4 * 10 1/2 = 7/4 * 21/2 = 147/8 = 18 3/8
