一、口算。
$150 - 90 =$ $360×20 =$ $860÷4 =$
$52×50 =$ $54 - 38 =$ $330×30 =$
$945÷9 =$ $50×42 =$ $180÷90 =$
$65 + 99 =$ $800÷5 =$ $700 - 30 =$
$65×20 =$ $25 + 68 =$ $120×8 =$
$246÷6 =$ $102×9 =$ $800÷8 =$
$205×3 =$ $304÷4 =$ $15 + 77 =$
$500 + 250 =$ $49×20 =$ $240×30 =$
$600÷12 =$ $640÷4 =$ $91 - 74 =$
$100 - 56 =$ $26×70 =$ $123÷3 =$

一、60 7200 215
2600 16 9900
105 2100 2
164 160 670
1300 93 960
41 918 100
615 76 92
750 980 7200
50 160 17
44 1820 41

二、计算下面图形中未知角的度数。

二、∠1=180°×(4−2)−80°−95°−113°=72°
∠2=180°×(5−2)−120°−135°−88°−90°=107°