$23 + 18 =$ $310 - 50 =$ $1200 - 600 =$
$140 - 80 =$ $500 + 900 =$ $15 + 72 =$
$70 + 340 =$ $87 - 39 =$ $90 - 16 =$
$89 - 33 =$ $34 + 30 =$ $280 + 300 =$
$80 + 800 =$ $520 - 500 =$ $82 - 52 =$
$55 - 47 =$ $72 + 12 =$ $150 + 80 =$
$90 + 50 =$ $1100 - 600 =$ $70 - 24 =$
$66 + 24 =$ $19 + 21 =$ $4000 - 3000 =$
$42 + 29 =$ $270 - 70 =$ $90 + 190 =$
$3700 - 700 =$ $50 + 80 =$ $1200 - 300 =$

一、41 260 600
60 1400 87
410 48 74
56 64 580
880 20 30
8 84 230
140 500 46
90 40 1000
71 200 280
3000 130 900

$384 + 97$ $553 + 908$ * $644 + 578$

二、481 1461 1222