一、口算。
$88 - 9 =$ $90 - 80 =$ $44 + 7 =$
$50 + 41 =$ $7 + 4 =$ $12 - 8 =$
$31 - 5 =$ $65 - 50 =$ $55 + 30 =$
$73 + 20 =$ $47 + 5 =$ $83 - 20 =$
$57 - 30 =$ $40 - 20 =$ $43 + 7 =$
$9 + 27 =$ $18 + 3 =$ $69 - 50 =$
$20 + 70 =$ $62 - 4 =$ $6 + 25 =$
$92 - 30 =$ $16 + 7 =$ $57 - 9 =$
$46 + 8 =$ $53 - 4 =$ $68 + 4 =$
$87 - 60 =$ $57 + 30 =$ $88 - 40 =$

一、79 10 51
91 11 4
26 15 85
93 52 63
27 20 50
36 21 19
90 58 31
62 23 48
54 49 72
27 87 48

二、连一连。

二、