a) 2 3/7 + 5/3 = 17/7 + 5/3 = (17*3 + 5*7)/21 = (51 + 35)/21 = 86/21 = 4 2/21
b) 7 13/15 - 2 7/10 = 118/15 - 27/10 = (118*10 - 27*15)/150 = (1180 - 405)/150 = 775/150 = 31/6 = 5 1/6
c) 1 1/2 * 3 1/3 = 3/2 * 10/3 = 30/6 = 5
d) 9 1/5 : 5 3/5 = 46/5 : 28/5 = 46/5 * 5/28 = 46/28 = 23/14 = 1 9/14
Ответ: a) 4 2/21 b) 5 1/6 c) 5 d) 1 9/14