Question

[Lê Phương Linh]

Answer 1

[Yen Nhi]

Bài 1:

\(\dfrac{4}{7}+\dfrac{5}{13}=\dfrac{52+35}{91}=\dfrac{87}{91}\)

\(\dfrac{2}{15}+\dfrac{7}{5}=\dfrac{2+21}{15}=\dfrac{23}{15}\)

\(\dfrac{41}{15}.\dfrac{20}{13}=\dfrac{41.20}{15.13}=\dfrac{164}{39}\)

\(\dfrac{3}{5}+2=\dfrac{3+10}{5}=\dfrac{13}{5}\)

\(4-\dfrac{13}{4}=\dfrac{16-13}{4}=\dfrac{3}{4}\)

\(2:\dfrac{1}{3}=2.3=6\)

Bài 2:

\(\dfrac{7}{5}-x=\dfrac{3}{10}\Rightarrow x=\dfrac{7}{5}-\dfrac{3}{10}\Rightarrow x=\dfrac{11}{10}\)

\(\dfrac{4}{7}:x=\dfrac{5}{15}\Rightarrow x=\dfrac{4}{7}:\dfrac{5}{15}\Rightarrow x=\dfrac{12}{7}\)

Bài 3:

\(\dfrac{6}{7}+\dfrac{5}{12}+\dfrac{7}{12}+\dfrac{1}{7}=\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{5}{12}+\dfrac{7}{12}\right)=2\)

\(\dfrac{4}{13}.\dfrac{6}{13}+\dfrac{4}{13}.\dfrac{7}{13}\)\(=\dfrac{4}{13}.\left(\dfrac{6}{13}+\dfrac{7}{13}\right)=1\)

Bài 4:

\(2\dfrac{3}{5}=\dfrac{2.5+3}{5}=\dfrac{13}{5}\)

\(7\dfrac{1}{2}=\dfrac{7.2+1}{2}=\dfrac{15}{2}\)

\(4\dfrac{3}{8}=\dfrac{4.8+3}{8}=\dfrac{35}{8}\)

\(5\dfrac{4}{11}=\dfrac{5.11+4}{11}=\dfrac{59}{11}\)

\(9\dfrac{1}{12}=\dfrac{9.12+1}{12}=\dfrac{109}{12}\)

\(3\dfrac{7}{9}=\dfrac{3.9+7}{9}=\dfrac{34}{9}\)

Bài 5:

Số bao màu xanh chiếm: \(1200.\dfrac{30}{100}=360\) bao

Số bao màu trắng chiếm: \(1200.\dfrac{45}{100}=540\) bao

Số bao màu vàng: \(1200-360-540=300\) bao.