1/5 ; 1/7

1/5

1/7

1/5

1/7

giúp mình với, đi mà

\(\dfrac{18}{21}=\dfrac{6}{7}\)=\(\dfrac{12}{14}=\dfrac{36}{42}\)=\(\dfrac{90}{150}=\dfrac{3}{5}\)=\(\dfrac{12}{20}=\dfrac{60}{100}=\dfrac{21}{35}\)

\(\dfrac{18}{21}=\dfrac{12}{14}=\dfrac{6}{7}=\dfrac{36}{42}\)

\(\dfrac{90}{150}=\dfrac{12}{20}=\dfrac{60}{100}=\dfrac{3}{5}=\dfrac{21}{35}\)

\(\dfrac{21}{35}=\dfrac{21:7}{35:7}=\dfrac{3}{5}=\dfrac{3\times2}{5\times2}=\dfrac{6}{10}\)

Chọn B

B

\(a,\dfrac{3}{4}:\dfrac{6}{x}=\dfrac{5}{4}\\ \dfrac{6}{x}=\dfrac{3}{4}:\dfrac{5}{4}\\ \dfrac{6}{x}=\dfrac{3}{5}\\ x=6:\dfrac{3}{5}\\ x=10\\ b,\left(x+\dfrac{7}{4}\right)\times\dfrac{2}{3}=6\\ x+\dfrac{7}{4}=6:\dfrac{2}{3}\\x+\dfrac{7}{4}=9\\ x=9-\dfrac{7}{4}\\ x=\dfrac{29}{4}\)

giúp mình đi, sao dạo này ít ngừi giúp qué zại

a) \(\dfrac{3}{4}\div\dfrac{6}{x}=\dfrac{5}{4}\)

            \(\dfrac{6}{x}=\dfrac{3}{4}\div\dfrac{5}{4}\)

            \(\dfrac{6}{x}=\dfrac{3}{5}\)

            \(x=\left(6\div3\right)\times5\)

           \(x=10\)

b) \(\left(x+\dfrac{7}{4}\right)\times\dfrac{2}{3}=6\)

     \(x+\dfrac{7}{4}=6\div\dfrac{2}{3}\)

     \(x+\dfrac{7}{4}=9\)

     \(x=9-\dfrac{7}{4}\)

    \(x=\dfrac{29}{4}\)

A

A

A

giúp mình với

Cả 2 tổ quét được số phần sân trường là.:
7/10 + 1/5 = 7/10 + 2/10 = 9/10 (sân trường)

\(\dfrac{5}{7}=\dfrac{5\times3}{7\times3}=\dfrac{15}{21};\dfrac{6}{21}\)

\(\dfrac{20}{28}=\dfrac{20:4}{28:4}=\dfrac{5}{7};\dfrac{5}{7}\)

5/7=15/21

6/21 giữ nguyên

5/7=20/28 

20/28 giữ nguyên

5/7 và 6/21

mẫu số chung: 7

giữ nguyên \(\dfrac{5}{7}\)

\(\dfrac{6}{21}=\dfrac{6:3}{21:3}=\dfrac{2}{7}\)

5/7 và 20/28

mẫu số chung: 7

giữ nguyên \(\dfrac{5}{7}\)

\(\dfrac{20}{28}=\dfrac{20:4}{28:4}=\dfrac{5}{7}\)

A

A

A