一、口算。
2 + 9 = 28 + 3 = 68 + 4 =
35 + 6 = 91 - 8 = 12 - 7 =
78 - 50 = 58 + 6 = 6 + 15 =
56 + 20 = 41 - 30 = 85 - 6 =
83 - 6 = 45 + 5 = 69 + 30 =
7 + 26 = 47 - 9 = 53 - 50 =
79 - 20 = 22 + 60 = 17 + 70 =
45 + 8 = 80 - 50 = 74 - 20 =
37 - 9 = 20 + 38 = 62 + 8 =
34 + 9 = 73 - 5 = 50 - 20 =

一、11 31 72
41 83 5
28 64 21
76 11 79
77 50 99
33 38 3
59 82 87
53 30 54
28 58 70
43 68 30

二、给下面的算式排排队。(填序号)

()＜()＜()＜()＜()

二、⑤ ③ ① ②
④