a) \(\frac{59}{42}\)
b) \(\frac{17}{36}\)
c) \(\frac{5}{51}\)
d) \(\frac{4}{7}\)

a: \(\frac56+\frac47=\frac{35}{42}+\frac{24}{42}=\frac{35+24}{42}=\frac{59}{42}\)

b: \(\frac54-\frac79=\frac{45}{36}-\frac{28}{36}=\frac{45-28}{36}=\frac{17}{36}\)

c: \(\frac{15}{17}\times\frac19=\frac{15\times1}{17\times9}=\frac{15}{153}=\frac{5}{51}\)

d: \(\frac37:\frac68=\frac37:\frac34=\frac37\times\frac43=\frac47\)

\(\frac{2}{5}.\frac{3}{4}+\frac{6}{15}:\frac{4}{9}.5=\frac{6}{20}+\frac{9}{10}.5=\frac{6}{20}.\frac{9}{2}=\frac{27}{20}\)

\(\frac{2}{5}\cdot\frac{3}{4}+\frac{6}{15}\cdot\frac{9}{4}\cdot5=\frac{3}{10}+\frac{45}{10}=\frac{48}{10}=\frac{24}{5}\)

p/s : tự quy đồng vs dấu "." là dấu nhân nhá

\(\frac{3}{10}+\frac{9}{2}\)

\(=\frac{24}{5}\)

\(\frac{2}{5}\)x \(\frac{3}{4}\)+ \(\frac{6}{15}\): \(\frac{4}{9}\)x 5

= \(\frac{3}{10}\)+ \(\frac{6}{15}\)x \(\frac{9}{4}\)x 5

= \(\frac{18}{60}\)+ \(\frac{24}{60}\)x \(\frac{9}{4}\)x 5

= \(\frac{7}{10}\)x \(\frac{9}{4}\)x 5

= \(\frac{63}{40}\)x 5

= \(\frac{63}{8}\)

\(\frac{2}{5}×\frac{3}{4}+\frac{6}{15}:\frac{4}{9}×5\)

\(=\frac{3}{10}+\frac{6}{15}×\frac{9}{4}×5\)

\(=\frac{3}{10}+\frac{9}{10}×5\)

\(=\frac{3}{10}+\frac{9}{2}\)

\(=\frac{3}{10}+\frac{45}{10}\)

\(=\frac{3+45}{10}\)

\(=\frac{48}{10}=\frac{24}{5}=4,8\)

\(\frac{3}{10}+\frac{9}{10}\cdot5=\frac{3}{10}+\frac{45}{10}=\frac{48}{10}=\frac{24}{5}\)

khong can ghi de bai nha

a)\(\frac{27}{5}\text{x}\frac{91}{12}\text{x}\frac{125}{9}\text{x}\frac{96}{13}=\frac{27}{9}\text{x}\frac{91}{13}\text{x}\frac{125}{5}\text{x}\frac{96}{12}=3\text{x}7\text{x}25\text{x}8\)

Đến đây tự tính nha !

b)\(\frac{2539}{35}\text{x}\frac{7}{90}+\frac{561}{35}\text{x}\frac{7}{90}=\frac{7}{90}\text{x}\left(\frac{2539}{35}+\frac{561}{35}\right)=\frac{7}{90}\text{x}\frac{3100}{35}=\frac{3100}{90}\text{x}\frac{7}{35}=\frac{310}{9}\text{x}\frac{1}{5}=\frac{62}{9}\)

1. 27/5 x 91/12 x 125/9 x 96/13

2. 2539/35 x 7/90 + 561/35 x 7/90

3. 31/7 : (2/5 x 31/7)

4. (29 x 15/23 x 36/29) : 5/23

(7x6=5+2+6x7) =

2\(\frac{1}{2}\), 3\(\frac{1}{2}\), 3\(\frac{5}{6}\), 7\(\frac{3}{4}\),7\(\frac{5}{6}\), 9\(\frac{1}{15}\)

ban nho bo cai o vuong nhe tai may