一、口算。
$7y×5=$
$290+210=$
$65.5÷10=$
$5.7÷3=$
$3.7×3=$
$5.8×100=$
$11.3-2.5=$
$0.99÷11=$
$6.05-5.6=$
$960÷6=$
$390-327=$
$5×207=$
$1.72n-0.4n=$
$10.5×2=$
$9.3x÷3=$
$13.2÷4=$
$1.3×40=$
$7.2a+2.8a=$
$1.5-0.45=$
$140÷35=$
$0.85×20=$
$1.25×8=$
$9.7+12.5=$
$120×50=$
$0.96÷48=$
$6.4÷16=$
$5.63+1.65=$
$11.41+5.8=$
$0.32×500=$
$2.25÷25=$

7y×5=35y
290+210=500
65.5÷10=6.55
5.7÷3=1.9
3.7×3=11.1
5.8×100=580
11.3-2.5=8.8
0.99÷11=0.09
6.05-5.6=0.45
960÷6=160
390-327=63
5×207=1035
1.72n-0.4n=1.32n
10.5×2=21
9.3x÷3=3.1x
13.2÷4=3.3
1.3×40=52
7.2a+2.8a=10a
1.5-0.45=1.05
140÷35=4
0.85×20=17
1.25×8=10
9.7+12.5=22.2
120×50=6000
0.96÷48=0.02
6.4÷16=0.4
5.63+1.65=7.28
11.41+5.8=17.21
0.32×500=160
2.25÷25=0.09

二、计算下面各图形的面积。
1.
2.

1. $12×8-(4+8)×4÷2=72(cm^2)$
2. $4×4÷2+6×6÷2+(7+4+6)×6÷2=77(dm^2)$