`3/7+x=5/8`

`=>x=5/8-3/7`

`=>x=35/56-24/56`

`=>x=11/56`

\(\dfrac{3}{7}\) + x = \(\dfrac{5}{8}\)

        x  = \(\dfrac{5}{8}\) - \(\dfrac{3}{7}\)

       x = \(\dfrac{11}{56}\)

Chiều rộng mảnh vườn:
\(60\times\dfrac{3}{5}=36\left(cm\right)\)
Chu vi mảnh vườn:
\(\left(60+36\right)\times2=192\left(cm\right)\)
Diện tích mảnh vườn:
\(60\times36=2160\left(cm^2\right)\)

#DatNe

chiều rộng; 60:5x3=36 cm

Chu vi: (60+36)x2=192 cm

diện tích : 60 x 36=2160 cm²

\(\dfrac{3}{4}:2=\dfrac{3}{4}\times\dfrac{1}{2}=\dfrac{3}{8}\)

3/4:2=0,735

\(\dfrac{2}{3}\times\dfrac{6}{7}=\dfrac{12}{21}=\dfrac{4}{7}\)

#DatNe

    \(\dfrac{2}{3}\) \(\times\) \(\dfrac{6}{7}\)

=  \(\dfrac{4}{7}\)

\(\dfrac{5}{6}\times3+\dfrac{20}{6}\times2-1:\dfrac{6}{5}\)
\(=\dfrac{5}{6}\times3-\dfrac{5}{6}+\dfrac{20}{6}\times2\)
\(=\dfrac{5}{6}\times\left(3-1\right)+\dfrac{20}{6}\times2\)
\(=\dfrac{5}{6}\times2+\dfrac{20}{6}\times2\)
\(=\left(\dfrac{5}{6}+\dfrac{20}{6}\right)\times2\)
\(=\dfrac{25}{6}\times2\)
\(=\dfrac{25}{3}\)

#DatNe

\(\dfrac{5}{6}\) \(\times\) 3 + \(\dfrac{20}{6}\) \(\times\) 2 - 1 : \(\dfrac{6}{5}\)

= \(\dfrac{5}{6}\) \(\times\) 3 + \(\dfrac{20}{6}\) \(\times\) 2 - \(\dfrac{5}{6}\)

= \(\dfrac{5}{6}\) \(\times\) 3 + \(\dfrac{5}{6}\) \(\times\) 8 - \(\dfrac{5}{6}\) \(\times\)1

= \(\dfrac{5}{6}\) \(\times\) ( 3 + 8 - 1)

= \(\dfrac{5}{6}\) \(\times\)10

= \(\dfrac{25}{3}\)

\(\dfrac{20}{16}-\dfrac{3}{4}=\dfrac{5}{4}-\dfrac{3}{4}=\dfrac{2}{4}=\dfrac{1}{2}\)
#DatNe

20/16=5/4

5/4-2/4=3/4

y x \(\dfrac{1}{3}\) = 6

y = 6 : \(\dfrac{1}{3}\)

y = 18

\(y\times\dfrac{1}{3}=6\)
\(y=6:\dfrac{1}{3}\)
\(y=6\times3=18\)
#DatNe

\(\dfrac{3}{15}+\dfrac{2}{5}=\dfrac{1}{5}+\dfrac{2}{5}=\dfrac{3}{5}\)
#DatNe

\(\dfrac{3}{15}+\dfrac{2}{5}=\dfrac{1}{5}+\dfrac{2}{5}=\dfrac{3}{5}\)

5/7=5x9/7x9=45/63

4/9=4x7/9x7=28/63

=>đáp án B

C

\(\dfrac{1}{2}\times\dfrac{3}{4}:\dfrac{6}{5}=\dfrac{3}{8}:\dfrac{6}{5}=\dfrac{5}{16}\)

\(\dfrac{2}{3}+\dfrac{1}{6}:\dfrac{7}{12}=\dfrac{2}{3}+\dfrac{2}{7}=\dfrac{14}{21}+\dfrac{6}{21}=\dfrac{20}{21}\)

\(8\times\dfrac{3}{5}:\dfrac{12}{5}=\dfrac{24}{5}:\dfrac{12}{5}=2\)

\(\dfrac{4}{9}+\dfrac{3}{4}-\dfrac{1}{3}=\dfrac{16}{36}+\dfrac{27}{36}-\dfrac{12}{36}=\dfrac{31}{36}\)