一、解方程。
$2.5x - 3.75 = 40$ $4x - 1.5x = 6$ $0.4×0.8 + 0.5x = 7$
$1.4x + 3.6 = 7.8$ $4×(x - 15.5) = 4.8$ $15x÷(5×0.5) = 10.5$
$x-\frac{7}{12}=\frac{3}{4}$ $0.2x + 0.7x = 5.4$ $4x - 4.6 + 2.4 = 9.8$
$x+\frac{1}{3}=\frac{9}{10}$ $x-\frac{14}{15}=\frac{11}{30}$ $x-\frac{5}{36}+\frac{5}{9}=\frac{17}{18}$
$x-\frac{5}{12}=\frac{1}{3}$ $x+\frac{1}{4}=\frac{7}{5}$ $16x-\frac{1}{6}=\frac{23}{6}$

$x = 17.5x = 2.4x = 13.36x = 3x = 16.7x = 1.75x = \frac{4}{3}x = 6x = 3x = \frac{17}{30}x = \frac{13}{10}x = \frac{19}{36}x = \frac{3}{4}x = \frac{23}{20}x = \frac{1}{4}$

二、计算下面各题，怎样简便就怎样计算。
$4.58 + 2.39 + 5.42 + 7.61$ $2-\frac{6}{11}+\frac{7}{22}-\frac{5}{11}$ $(15.3 - 2.8×3.5)÷0.5$
$26.7 - 0.5×0.5 - 0.75$ $\frac{4}{7}-\frac{1}{8}+\frac{5}{7}-\frac{7}{8}$ $0.48÷[0.2×(0.8 - 0.32)]$
$3.72×3.5 + 6.28×3.5$ $\frac{4}{9}+\frac{1}{17}+\frac{5}{9}-\frac{6}{17}$ $20 - 24.36÷(3.5×1.2)$
$(8 - 2.75)÷2.5 + 1.9$ $\frac{2}{7}+(\frac{3}{5}+\frac{1}{7})-\frac{1}{5}$ $28.9 - 15.5÷6.2 - 3.4$
$8.4 + (3.5 - 0.75)×0.4$ $\frac{11}{15}+\frac{7}{8}-(\frac{11}{15}-\frac{1}{8})$ $15.6÷[(1.62 - 0.9)÷0.3]$

$20 1\frac{7}{22} 1125.7 \frac{2}{7} 535 \frac{12}{17} 14.24 \frac{29}{35} 239.5 1 6.5$