Đáp án:
Giải thích các bước giải:
Bài 1
a, 3$\frac{4}{5}$ - 2 $\frac{3}{4}$ : 1$\frac{1}{8}$ = $\frac{19}{5}$ - $\frac{11}{4}$ : $\frac{9}{8}$ = $\frac{19}{2}$ - $\frac{22}{9}$ = $\frac{61}{45}$
b, 4$\frac{5}{7}$ : 1$\frac{5}{6}$ + 2$\frac{7}{15}$ x $\frac{21}{74}$ = $\frac{33}{7}$ : $\frac{11}{6}$ + $\frac{37}{15}$ x $\frac{21}{74}$ = $\frac{18}{7}$ + $\frac{7}{10}$ = $\frac{229}{70}$
Bài 2
a, 5$\frac{3}{4}$ : 3 + 2$\frac{1}{4}$ x $\frac{1}{3}$ - $\frac{3}{8}$ = $\frac{23}{4}$ x $\frac{1}{3}$ + $\frac{9}{4}$ x $\frac{1}{3}$ - $\frac{3}{8}$ = $\frac{1}{3}$ ($\frac{23}{4}$ + $\frac{9}{4}$ ) - $\frac{3}{8}$ = $\frac{1}{3}$ x 8 - $\frac{3}{8}$ = $\frac{8}{3}$ - $\frac{3}{8}$ = $\frac{55}{24}$
b, $\frac{3}{5}$ : $\frac{5}{6}$ : $\frac{6}{7}$ : $\frac{7}{8}$ + $\frac{2}{5}$ + $\frac{23}{35}$ = $\frac{3}{5}$ X $\frac{6}{5}$ X $\frac{7}{6}$ x $\frac{8}{7}$ + $\frac{14}{35}$ + $\frac{23}{35}$ = $\frac{24}{25}$ + $\frac{37}{35}$ = $\frac{353}{175}$
Bài 3
a, $\frac{7}{4}$ - X x $\frac{4}{3}$ = $\frac{5}{19}$
X x $\frac{4}{3}$ = $\frac{7}{4}$ - $\frac{5}{19}$
X = $\frac{113}{76}$ : $\frac{4}{3}$
X = $\frac{339}{304}$
b, X x $\frac{1}{2}$ + $\frac{3}{2}$ x X = $\frac{4}{5}$
X($\frac{1}{2}$ + $\frac{3}{2}$ ) = $\frac{4}{5}$
X x 2 = $\frac{4}{5}$
X = $\frac{4}{5}$ : 2
X = $\frac{2}{5}$
