nói chung=55/3

cách làm

\(\frac{8}{9}+\frac{1}{3}=\frac{8}{9}+\frac{3}{9}=\frac{11}{9}\)

\(\frac{8}{9}+\frac{1}{3}=\frac{8}{9}+\frac{3}{9}=\frac{11}{9}\)

\(\frac{24}{15}-\frac{20}{25}=\frac{24}{15}-\frac{4}{5}=\frac{24}{15}-\frac{12}{15}=\frac{12}{15}\)

\(3\frac{1}{6}\times2\frac{3}{5}=\frac{19}{6}\times\frac{13}{5}=\frac{247}{30}\)

\(2\frac{1}{10}\div2\frac{2}{5}=\frac{21}{10}\div\frac{12}{5}=\frac{21}{10}\times\frac{5}{12}=\frac{7}{8}\)

= 480 nha bn

chúc hk tốt

\( \frac{48.700-24.45.20}{45-40+35-30+25-20+15-10+5}\)

\(=\frac{48.700-24.2.10.45}{5+5+5+5+5}\)
\(=\frac{48.700-48.450}{5.5}\)
\(=\frac{48.\left(700-450\right)}{25}\)
\(=\frac{48.250}{25}\)
\(=480\)
 

bài 6 \(\frac{2}{2\times4}+\frac{2}{4\times6}+\frac{2}{6\times8}+\ldots+\frac{2}{80\times82}+\frac{2}{82\times84}\)

= \(\frac12-\frac14+\frac14-\frac16+\frac16-\cdots+\frac{1}{80}-\frac{1}{82}+\frac{1}{82}-\frac{1}{84}\)

= \(\frac12-\left(\frac14-\frac14\right)-\left(\frac16-\frac16\right)-\cdots-\left(\frac{1}{82}-\frac{1}{82}\right)-\frac{1}{84}\)

=\(\frac12-0-0-\frac{1}{84}\)

=\(\frac12\) - \(\frac{1}{84}\)

=\(\frac{42}{84}-\frac{1}{84}\)

=\(\frac{41}{84}\)

Bài 7

a)\(\frac{19}{4}=4\frac34\)

b)\(\frac{27}{5}=5\frac25\)

c)\(\frac{56}{8}=7\frac08\)

 \(\frac{10}{2000}:\frac{10}{2000}.\frac{4}{5}+\frac{1}{5}+20\%+80\%\)

=\(1.\frac{4}{5}+\frac{1}{5}+\frac{1}{5}+\frac{4}{5}\)

=\(\frac{4}{5}.2+\frac{1}{5}.2\)

=\(\frac{8}{5}+\frac{2}{5}\)

=\(\frac{10}{5}=2\)

=

a) \(\frac{15}{16}:\frac{25}{24}=\frac{15}{16}.\frac{24}{25}=\frac{9}{10}\)

b) \(10:\frac{5}{3}=10.\frac{3}{5}=6\)

c) \(\frac{5}{3}:10=\frac{5}{3}.\frac{1}{10}=\frac{5}{30}=\frac{1}{6}\)

a. \(\frac{15}{16}:\frac{25}{24}=\frac{15}{16}.\frac{24}{25}=\frac{9}{10}\)

b. \(10:\frac{5}{3}=10.\frac{3}{5}=6\)

c. \(\frac{5}{3}:10=\frac{5}{3}.\frac{1}{10}=\frac{1}{6}\)