一、口算。
$16 - 7 =$
$6 + 7 =$
$6 + 6 - 3 =$
$6 + 8 =$
$11 - 6 =$
$15 - 3 + 6 =$
$16 - 8 =$
$9 + 8 =$
$13 - 5 - 3 =$
$15 - 6 =$
$14 - 9 =$
$5 + 5 + 4 =$
$13 - 9 =$
$5 + 6 =$
$8 + 8 - 9 =$
$7 + 8 =$
$11 - 5 =$
$11 - 7 + 6 =$
$17 - 9 =$
$13 + 6 =$
$2 + 9 + 2 =$
$8 + 10 =$
$17 - 7 =$
$18 - 9 - 9 =$
$15 - 5 =$
$4 + 9 =$
$10 - 4 + 9 =$
$9 + 3 =$
$14 - 6 =$
$16 - 9 - 5 =$

一、9 13 9
14 5 18
8 17 5
9 5 14
4 11 7
15 6 10
8 19 13
18 10 0
10 13 15
12 8 2

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

二、6 7 9
7 13 5
15 6 7