一、口算。
$80\div1.6=$ $6.2 + 1.7=$ $8.5 - 6.3=$
$0.48 + 0.16=$ $6.08\div0.4=$ $1.5\times80=$
$2.2\times0.4=$ $60.5 + 3.05=$ $1.58 - 0.59=$
$0.85\div0.05=$ $0.16\times40=$ $0.28 + 0.82=$
$2.3\times0.08=$ $0.34 + 0.27=$ $50.7 - 3.7=$
$\frac{23}{25}-\frac{1}{4}=$ $\frac{5}{6}-\frac{2}{5}=$ $\frac{9}{10}+\frac{5}{2}=$
$1+\frac{7}{12}=$ $\frac{4}{7}+\frac{5}{6}=$ $\frac{5}{8}-\frac{1}{2}=$
$\frac{9}{10}-\frac{5}{16}=$ $\frac{2}{5}+\frac{1}{3}=$ $\frac{4}{9}+\frac{4}{9}=$
$\frac{2}{9}+\frac{3}{4}=$ $\frac{17}{24}-\frac{5}{12}=$ $\frac{4}{7}-\frac{4}{21}=$
$\frac{5}{13}-\frac{5}{26}=$ $\frac{3}{10}+\frac{1}{2}=$ $\frac{1}{2}+\frac{5}{14}=$

$50 7.9 2.20.64 15.2 1200.88 63.55 0.9917 6.4 1.10.184 0.61 47\frac{67}{100} \frac{13}{30} \frac{17}{5}1\frac{7}{12} \frac{59}{42} \frac{1}{8}\frac{47}{80} \frac{11}{15} \frac{8}{9}\frac{35}{36} \frac{7}{24} \frac{8}{21}\frac{5}{26} \frac{4}{5} \frac{6}{7}$

二、计算下面各题，怎样简便就怎样计算。
$29\div14.5\times1.8$ $7.2 - 3.25\div1.3\times0.7$ $8.25\div0.25 - 1.25\div0.25$

3.6 5.45 28