《2025年心算口算巧算六年级上册北师大版》

$\frac{3}{4}x + \frac{5}{12}x = 57$

答案： $\frac{9}{12}x + \frac{5}{12}x = 57$
$\frac{14}{12}x = 57$
$\frac{7}{6}x = 57$
$x = 57 ÷ \frac{7}{6}$
$x = 57 × \frac{6}{7}$
$x = \frac{342}{7}$

$x + \frac{2}{3}x = \frac{2}{9}$

答案： $\frac{3}{3}x + \frac{2}{3}x = \frac{2}{9}$
$\frac{5}{3}x = \frac{2}{9}$
$x = \frac{2}{9} ÷ \frac{5}{3}$
$x = \frac{2}{9} × \frac{3}{5}$
$x = \frac{2}{15}$

$3x + \frac{13}{35} = \frac{5}{7}$

答案： $3x = \frac{5}{7} - \frac{13}{35}$
$3x = \frac{25}{35} - \frac{13}{35}$
$3x = \frac{12}{35}$
$x = \frac{12}{35} ÷ 3$
$x = \frac{12}{35} × \frac{1}{3}$
$x = \frac{4}{35}$

$\frac{9}{10}x + \frac{1}{2} = \frac{3}{4}$

答案： $\frac{9}{10}x = \frac{3}{4} - \frac{1}{2}$
$\frac{9}{10}x = \frac{3}{4} - \frac{2}{4}$
$\frac{9}{10}x = \frac{1}{4}$
$x = \frac{1}{4} ÷ \frac{9}{10}$
$x = \frac{1}{4} × \frac{10}{9}$
$x = \frac{5}{18}$

$x + \frac{3}{8}x = 121$

答案： $\frac{8}{8}x + \frac{3}{8}x = 121$
$\frac{11}{8}x = 121$
$x = 121 ÷ \frac{11}{8}$
$x = 121 × \frac{8}{11}$
$x = 88$

$5x - \frac{5}{7} = \frac{5}{7}$

答案： $5x = \frac{5}{7} + \frac{5}{7}$
$5x = \frac{10}{7}$
$x = \frac{10}{7} ÷ 5$
$x = \frac{10}{7} × \frac{1}{5}$
$x = \frac{2}{7}$

$3x - \frac{1}{3}x = 12$

答案： $\frac{9}{3}x - \frac{1}{3}x = 12$
$\frac{8}{3}x = 12$
$x = 12 ÷ \frac{8}{3}$
$x = 12 × \frac{3}{8}$
$x = \frac{9}{2}$

$\frac{3}{4}x + \frac{1}{4} = \frac{3}{8}$

答案： $\frac{3}{4}x = \frac{3}{8} - \frac{1}{4}$
$\frac{3}{4}x = \frac{3}{8} - \frac{2}{8}$
$\frac{3}{4}x = \frac{1}{8}$
$x = \frac{1}{8} ÷ \frac{3}{4}$
$x = \frac{1}{8} × \frac{4}{3}$
$x = \frac{1}{6}$

$2x + \frac{3}{2}x = \frac{7}{16}$

答案： $\frac{4}{2}x + \frac{3}{2}x = \frac{7}{16}$
$\frac{7}{2}x = \frac{7}{16}$
$x = \frac{7}{16} ÷ \frac{7}{2}$
$x = \frac{7}{16} × \frac{2}{7}$
$x = \frac{1}{8}$