一、口算。
$530 - 70 =$ $420 ÷ 30 =$ $0.77 + 1.33 =$
$660 ÷ 60 =$ $39 + 14 =$ $10 - 0.09 =$
$24 × 50 =$ $280 ÷ 40 =$ $8.7 + 3 =$
$33 ÷ 11 =$ $28 × 50 =$ $0.76 - 0.36 =$
$80 - 21 =$ $6 × 800 =$ $8.9 - 8.84 =$
$420 ÷ 70 =$ $480 ÷ 40 =$ $1.3 - 0.24 =$
$24 + 57 =$ $230 + 680 =$ $8.3 - 5 =$
$270 ÷ 90 =$ $36 × 20 =$ $2.2 - 0.6 =$
$30 × 27 =$ $720 ÷ 3 =$ $5.5 + 3.32 =$
$560 ÷ 7 =$ $360 + 240 =$ $6.9 + 9.6 =$

一、460 14 2.1
11 53 9.91
1200 7 11.7
3 1400 0.4
59 4800 0.06
6 12 1.06
81 910 3.3
3 720 1.6
810 240 8.82
80 600 16.5

二、计算下面图形中未知角的度数。

二、∠1=180°-70°×2=40°
∠2=180°×(5-2)-126°-135°-99°-108°=72°