18．解方程．
| $\frac{3}{14}$x=1$\frac{4}{5}$ | $\frac{3}{4}$+x=$\frac{4}{5}$ | $\frac{8}{9}$-x=$\frac{1}{3}$ |
| x+$\frac{1}{3}$=4 | $\frac{3}{4}$x=3 | $\frac{3}{4}$x=$\frac{1}{3}$ |
17．口算
0 162508 162516 162522 162526 162532 162534 162538 162544 162546 162552 162558 162562 162564 162568 162574 162576 162582 162586 162588 162592 162594 162598 162600 162602 162603 162604 162606 162607 162608 162610 162612 162616 162618 162622 162624 162628 162634 162636 162642 162646 162648 162652 162658 162664 162666 162672 162676 162678 162684 162688 162694 162702 199269
| $\frac{3}{14}$÷4 | $\frac{4}{5}$÷$\frac{4}{7}$ | $\frac{3}{5}$×$\frac{8}{69}$ |
| $\frac{3}{4}$×$\frac{4}{5}$ | $\frac{7}{24}$÷$\frac{3}{14}$ | $\frac{5}{33}$×$\frac{4}{5}$×$\frac{1}{2}$ |
| $\frac{3}{4}$+$\frac{1}{3}$ | 1-$\frac{8}{69}$ | $\frac{1}{5}$+$\frac{1}{2}$-$\frac{3}{5}$ |