一、口算。
30 + 6 = 13 - 7 = 10 + 70 =
69 - 60 = 5 + 9 = 8 + 2 =
4 + 90 = 50 - 30 = 73 - 3 =
91 - 1 = 50 + 40 = 4 + 8 =
30 + 5 = 14 - 5 = 12 - 6 =
59 - 50 = 9 + 40 = 8 + 60 =
80 + 8 = 8 + 3 = 16 - 8 =
66 - 60 = 15 - 8 = 70 + 3 =
4 + 70 = 9 + 20 = 77 - 7 =
92 - 90 = 80 - 40 = 7 + 9 =

一、36 6 80
9 14 10
94 20 70
90 90 12
35 9 6
9 49 68
88 11 8
6 7 73
74 29 70
2 40 16

二、在$□$里填合适的数。
$□$ - 3 = 80 $□$ + 30 = 90 $□$ - 9 = 90
$□$ + 30 = 36 $□$ - 20 = 60 5 + $□$ = 55
65 - $□$ = 60 $□$ + 9 = 49 70 - $□$ = 20

二、83 60 99
6 80 50
5 40 50