一、在$□$里填合适的数。
8 + $□$ = 15
$□$ + 5 = 12
11 - $□$ = 9
7 + $□$ = 14
12 - $□$ = 5
$□$ - 4 = 9
13 - $□$ = 9
$□$ + 7 = 13
6 + $□$ = 11
$□$ + 3 = 11
$□$ + 8 = 14
15 - $□$ = 9
$□$ + 4 = 12
13 - $□$ = 4
$□$ - 4 = 7
16 - $□$ = 8
$□$ - 8 = 9
7 + $□$ = 16
$□$ + 5 = 11
14 - $□$ = 9
$□$ - 5 = 6
$□$ - 9 = 2
16 - $□$ = 7
15 - $□$ = 6
4 + $□$ = 13
$□$ + 8 = 17
$□$ + 5 = 13

一、7 7 2
7 7 13
4 6 5
8 6 6
8 9 11
8 17 9
6 5 11
11 9 9
9 9 8

二、填一填。

二、12 6 13 5 14
7 15 10 16 9
17 9 11 7 13
14 9 13 7 12
11 15 8 17 9
13 7 11 8 12