二、计算下面各题，怎样简便就怎样计算。
$\frac{4}{15}+\frac{5}{12}-\frac{1}{6}$ $\frac{13}{10}-(\frac{3}{10}+\frac{7}{15})$ $\frac{11}{6}-\frac{3}{8}-\frac{5}{8}+\frac{5}{6}$

$\frac{31}{60} \frac{8}{15} \frac{5}{3}$

一、解方程。
$3x + 1.5 = 18$ $10x + 5\times2.5 = 30$ $40x\div5 = 19.2$
$7x + 2.4 = 6.6$ $23.5x + 21.5x = 315$ $4x - 3.5x = 0.56$
$3x\times0.4 = 1.32$ $x\div4 + 4\div10 = 2.4$ $2.2 + x + 4.6 = 15.04$
$x-\frac{5}{8}=\frac{2}{7}$ $x+\frac{1}{3}=\frac{7}{9}$ $\frac{1}{5}-\frac{3}{25}+x=\frac{3}{5}$
$x+\frac{1}{4}=\frac{5}{6}$ $x-\frac{7}{18}=\frac{11}{24}$ $\frac{8}{9}+x=\frac{1}{4}+\frac{5}{6}$

$x = 5.5x = 1.75x = 2.4x = 0.6x = 7x = 1.12x = 1.1x = 8x = 8.24x = \frac{51}{56}x = \frac{4}{9}x = \frac{13}{25}x = \frac{7}{12}x = \frac{61}{72}x = \frac{7}{36}$

二、计算下面各题，怎样简便就怎样计算。
$6.8 + 1.25\times6.8\times8$ $\frac{8}{5}+\frac{2}{7}-\frac{3}{5}+\frac{5}{7}$ $14.6\times7.3 - 7.3 + 6.4\times7.3$
$1.27 + 3.9 + 0.73 + 16.1$ $\frac{29}{24}-(\frac{5}{24}-\frac{4}{9})+\frac{5}{9}$ $9.6\times[0.52\div(6.13 - 5.73)]$
$4.25\div0.25 + 1.7\times0.6$ $\frac{7}{6}-(\frac{7}{10}-\frac{1}{3})+\frac{2}{5}$ $6.48\div[(0.4 + 0.5)\times0.6]$
$(8.14 - 3.75)\div2.5\div4$ $\frac{18}{11}-(\frac{7}{11}+\frac{3}{4})-\frac{1}{4}$ $(12.16 - 0.45\times6.4)\div0.4$
$15.4\times8 - 5.4\div0.125$ $\frac{15}{13}-\frac{3}{8}-\frac{5}{8}+\frac{11}{13}$ $2.7\times[30\times(0.9 - 0.55)]$

$74.8 2 14622 2 12.4818.02 1\frac{1}{5} 120.439 0 23.280 1 28.35$