15．脱式计算（能简算的用简算）．
| $10-\frac{2}{15}×\frac{5}{6}$ | $\frac{1}{4}×\frac{5}{6}+\frac{1}{6}×\frac{1}{4}$ | $（\frac{5}{6}+\frac{1}{4}）÷（\frac{7}{3}+\frac{5}{9}）$ | $（\frac{7}{10}+\frac{5}{6}-\frac{4}{5}）×30$ |
| $\frac{5}{8}+\frac{3}{7}+\frac{4}{7}$ | $25-\frac{7}{9}-\frac{2}{9}$ | $\frac{8}{13}-\frac{1}{7}+\frac{5}{13}$ | $（\frac{1}{2}-\frac{3}{8}）÷\frac{3}{4}$ |
14．直接写出得数．
0 157805 157813 157819 157823 157829 157831 157835 157841 157843 157849 157855 157859 157861 157865 157871 157873 157879 157883 157885 157889 157891 157895 157897 157899 157900 157901 157903 157904 157905 157907 157909 157913 157915 157919 157921 157925 157931 157933 157939 157943 157945 157949 157955 157961 157963 157969 157973 157975 157981 157985 157991 157999 199269
| $\frac{1}{6}$÷$\frac{1}{3}$= | $\frac{4}{5}$×$\frac{1}{4}$= | 9×$\frac{1}{27}$= | $\frac{1}{3}$-$\frac{1}{4}$= |
| $1\frac{2}{3}+\frac{3}{5}$= | $39÷\frac{13}{15}$= | $\frac{3}{4}÷6$= | $\frac{4}{5}-\frac{1}{2}$= |