3．
| 脱式计算，能简算的要简算． 7.28-（1.25+0.28） | 9990×200.8+1×2008 |
| 0.8×4×12.5×2.5 | $\frac{1}{5}$÷[（$\frac{2}{3}$+$\frac{1}{5}$）×$\frac{1}{13}$] |
| [（$\frac{8}{9}$+$\frac{4}{3}$）×$\frac{3}{4}$-$\frac{1}{4}$]÷$\frac{1}{12}$ | （$\frac{5}{9}$+$\frac{7}{18}$-$\frac{11}{12}$）×36． |
1．
0 159847 159855 159861 159865 159871 159873 159877 159883 159885 159891 159897 159901 159903 159907 159913 159915 159921 159925 159927 159931 159933 159937 159939 159941 159942 159943 159945 159946 159947 159949 159951 159955 159957 159961 159963 159967 159973 159975 159981 159985 159987 159991 159997 160003 160005 160011 160015 160017 160023 160027 160033 160041 199269
| 计算 75×$\frac{3}{15}$= | $\frac{9}{52}$×13= | $\frac{8}{5}$×$\frac{5}{24}$= | $\frac{2}{3}$÷$\frac{4}{15}$= |
| $\frac{4}{13}$×$\frac{3}{8}$= | $\frac{7}{52}$×$\frac{13}{28}$= | $\frac{11}{13}$÷$\frac{22}{39}$= | $\frac{9}{66}$×$\frac{11}{27}$= |
| $\frac{3}{5}$×$\frac{1}{12}$= | $\frac{7}{20}$÷$\frac{3}{5}$= | $\frac{7}{20}$÷$\frac{8}{15}$= | $\frac{9}{22}$÷18= |
| $\frac{5}{24}$×$\frac{4}{15}$= | $\frac{6}{7}$÷$\frac{3}{14}$= | $\frac{6}{25}$÷$\frac{3}{10}$= |