А) 5/6 + 1/4 = 10/12 + 3/12 = 13/12 = 1 1/12
б) 7/8 - 5/6 = 21/24 - 20/24 = 1/24
в) 3/10 - 4/15 = 9/30 - 8/30 = 1/30
г) 5 - 3 2/7 = 4 7/7 - 3 2/7 = 1 5/7
д) 4/9 * 3/8 = 1/6
е) 5/8 : 9/10 = 5/8 * 10/9 = 50/72 = 25/36
ж) 20/7 : 10/7 = 20/7 * 7/10 = 2
з) 33/5 * 10 = 33*2 = 66