一、口算。
$6 + 6 =$ $15 - 6 =$ $4 + 7 - 3 =$
$12 - 5 =$ $5 + 8 =$ $18 - 9 + 5 =$
$5 + 6 =$ $14 - 9 =$ $8 + 6 - 9 =$
$14 - 8 =$ $6 + 7 =$ $12 - 7 + 10 =$
$6 + 4 =$ $14 - 7 =$ $4 + 9 - 6 =$
$16 - 9 =$ $5 + 9 =$ $11 - 5 + 7 =$
$11 - 2 =$ $7 + 8 =$ $10 + 5 - 8 =$
$9 + 3 =$ $16 - 8 =$ $13 - 8 + 2 =$
$13 - 6 =$ $3 + 8 =$ $6 + 9 + 3 =$
$7 + 9 =$ $14 - 6 =$ $15 - 2 - 9 =$

一、12 9 8
7 13 14
11 5 5
6 13 15
10 7 7
7 14 13
9 15 7
12 8 7
7 11 18
16 8 4

二、在$□$里填合适的数。
$□ + 8 = 16$ $13 - □ = 5$ $□ - 2 = 10$
$9 + □ = 14$ $15 - □ = 6$ $8 + □ = 14$
$16 - □ = 7$ $□ + 3 = 12$ $10 + □ = 17$

二、8 8 12
5 9 6
9 9 7