\(x:\dfrac{2}{3}=\dfrac{6}{7}\)
\(x=\dfrac{6}{7}\times\dfrac{2}{3}\)
\(x=\dfrac{4}{7}\)

#DatNe

\(\dfrac{3}{7}+x=\dfrac{5}{8}\)
\(x=\dfrac{5}{8}-\dfrac{3}{7}\)
\(x=\dfrac{35}{56}-\dfrac{24}{56}\)
\(x=\dfrac{11}{56}\)
#DatNe

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

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

#DatNe

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

#DatNe

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

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

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

C

a/Diện tich xung quanh bể nước:
\(2\times1,2\times\left(2,8+1,5\right)=10,32\left(m^2\right)\)
b/Số lít nước có trong bể khi bể đầy nước:
\(2,8\times1,5\times1,2=5,04\left(m^3\right)=5040\left(l\right)\)
#DatNe