7．脱式计算，能简算的就简算．
| $\frac{7}{8}$÷$\frac{3}{4}$×$\frac{2}{3}$ | $\frac{7}{12}$×$\frac{3}{7}$×$\frac{5}{6}$ | $\frac{16}{5}$×$\frac{1}{2}$÷$\frac{2}{5}$ |
| $\frac{1}{4}$×6×$\frac{5}{6}$×8 | 2-$\frac{8}{9}$×$\frac{3}{8}$×$\frac{1}{7}$ | 75×$\frac{73}{76}$． |
6．认真填写得数．
| $\frac{3}{4}$×$\frac{2}{5}$= | $\frac{6}{7}$÷3= | $\frac{2}{7}$×21= | $\frac{5}{8}$×$\frac{2}{3}$= |
| $\frac{5}{6}$÷$\frac{2}{3}$= | 3÷$\frac{1}{3}$= | 1-$\frac{1}{2}$-$\frac{1}{3}$= | $\frac{1}{9}$÷$\frac{2}{3}$= |
| 5×$\frac{1}{2}$÷5= | 6×$\frac{1}{2}$÷$\frac{1}{4}$= | $\frac{5}{12}$-$\frac{1}{8}$×$\frac{2}{3}$= | $\frac{5}{7}$×$\frac{14}{15}$= |
5．X、Y、Z 是三个非零自然数，且X×$\frac{6}{5}$=Y×$\frac{8}{7}$=Z×$\frac{10}{9}$，那么X Y Z按照从大到小的顺序排列是（ ）
0 131263 131271 131277 131281 131287 131289 131293 131299 131301 131307 131313 131317 131319 131323 131329 131331 131337 131341 131343 131347 131349 131353 131355 131357 131358 131359 131361 131362 131363 131365 131367 131371 131373 131377 131379 131383 131389 131391 131397 131401 131403 131407 131413 131419 131421 131427 131431 131433 131439 131443 131449 131457 199269
| A． | X＞Y＞Z | B． | Z＞Y＞X | C． | Y＞X＞Z | D． | Y＞Z＞X |