《2025年心算口算巧算六年级上册北师大版》

解方程。
$\frac{2}{3}x + 5 = 8$
$(1 + \frac{1}{5})x = 6$
$4 + \frac{4}{5}x = 8$
$\frac{1}{3}x + \frac{4}{9}x = 8$
$\frac{1}{5}x - 4 = 3$
$\frac{2}{3}x - \frac{1}{6}x = 5$
$\frac{3}{4}x - 4 = 6$
$\frac{2}{9}x + \frac{2}{3} = 8$
$\frac{13}{20}x - 4 = \frac{9}{40}$
$\frac{5}{8}x + 4 = 20$
$\frac{5}{2}x - 2 = \frac{7}{5}$
$\frac{1}{2}x - \frac{2}{5}x = \frac{9}{2}$

答案： $\frac{2}{3}x + 5 = 8$
解：$\frac{2}{3}x = 3$，$x = 3×\frac{3}{2}=\frac{9}{2}$
$(1 + \frac{1}{5})x = 6$
解：$\frac{6}{5}x = 6$，$x = 6×\frac{5}{6}=5$
$4 + \frac{4}{5}x = 8$
解：$\frac{4}{5}x = 4$，$x = 4×\frac{5}{4}=5$
$\frac{1}{3}x + \frac{4}{9}x = 8$
解：$\frac{3}{9}x + \frac{4}{9}x = \frac{7}{9}x = 8$，$x = 8×\frac{9}{7}=\frac{72}{7}$
$\frac{1}{5}x - 4 = 3$
解：$\frac{1}{5}x = 7$，$x = 35$
$\frac{2}{3}x - \frac{1}{6}x = 5$
解：$\frac{4}{6}x - \frac{1}{6}x = \frac{1}{2}x = 5$，$x = 10$
$\frac{3}{4}x - 4 = 6$
解：$\frac{3}{4}x = 10$，$x = 10×\frac{4}{3}=\frac{40}{3}$
$\frac{2}{9}x + \frac{2}{3} = 8$
解：$\frac{2}{9}x = \frac{22}{3}$，$x = \frac{22}{3}×\frac{9}{2}=33$
$\frac{13}{20}x - 4 = \frac{9}{40}$
解：$\frac{13}{20}x = \frac{169}{40}$，$x = \frac{169}{40}×\frac{20}{13}=\frac{13}{2}$
$\frac{5}{8}x + 4 = 20$
解：$\frac{5}{8}x = 16$，$x = 16×\frac{8}{5}=\frac{128}{5}$
$\frac{5}{2}x - 2 = \frac{7}{5}$
解：$\frac{5}{2}x = \frac{17}{5}$，$x = \frac{17}{5}×\frac{2}{5}=\frac{34}{25}$
$\frac{1}{2}x - \frac{2}{5}x = \frac{9}{2}$
解：$\frac{5}{10}x - \frac{4}{10}x = \frac{1}{10}x = \frac{9}{2}$，$x = \frac{9}{2}×10=45$

$\frac{1}{2}x - \frac{2}{5}x = \frac{9}{2}$

答案： $\frac{5}{10}x - \frac{4}{10}x = \frac{9}{2}$
$\frac{1}{10}x = \frac{9}{2}$
$x = \frac{9}{2} × 10$
$x = 45$