a: Chiều rộng mảnh vườn là:

\(60\cdot\dfrac{2}{3}=40\left(m\right)\)

Diện tích mảnh vườn là \(60\cdot40=2400\left(m^2\right)\)

b: Diện tích trồng hoa là:

\(240:\dfrac{3}{5}=240\cdot\dfrac{5}{3}=400\left(m^2\right)\)

a) Chiều rộng mảnh vườn là:

\(60\times\dfrac{2}{3}=40\left(m\right)\)

Diện tích mảnh vườn đó là:

\(60\times40=2400\left(m^2\right)\)

b) Diện tích trồng hoa là:

\(240:\dfrac{3}{5}=400\left(m^2\right)\)

2,3-(-2)+(-2,3)+7,8+20%

=2+2,3-2,3+7,8+0,2

=2+8

=10

3x/20 = 21/5

3x.5 = 21.20

15x = 420

x = 420 : 15

x = 28

2,3-(-2)+(-2,3)+7,8+20%

=2,3-2,3+2+7,8+0,2

=2+8

=10

80

= 80 nhaa

\(\dfrac{2}{3}-\left(-\dfrac{5}{7}+\dfrac{2}{3}\right)=\dfrac{2}{3}+\dfrac{5}{7}-\dfrac{2}{3}=\dfrac{5}{7}\)

\(\dfrac{14}{13}+\left(\dfrac{-1}{13}-\dfrac{19}{20}\right)=\dfrac{14}{13}-\dfrac{1}{13}-\dfrac{19}{20}\)

\(=\dfrac{13}{13}-\dfrac{19}{20}=1-\dfrac{19}{20}=\dfrac{20}{20}-\dfrac{19}{20}\)

\(=\dfrac{1}{20}\)

=\(\dfrac{14}{13}\) + ( \(\dfrac{-20}{260}\) - \(\dfrac{247}{260}\) )

=\(\dfrac{14}{13}\) + \(\dfrac{-267}{260}\)

=\(\dfrac{280}{260}\) + \(\dfrac{-267}{260}\)

=\(\dfrac{13}{260}\)

=\(\dfrac{1}{20}\)

 

\(\dfrac{-13}{15}+\dfrac{5}{21}-\dfrac{1}{3}-\dfrac{2}{15}+\dfrac{2}{21}\)

\(=\left(\dfrac{-13}{15}-\dfrac{2}{15}\right)+\left(\dfrac{5}{21}+\dfrac{2}{21}-\dfrac{1}{3}\right)\)

\(=\dfrac{-15}{15}+\left(\dfrac{7}{21}-\dfrac{1}{3}\right)\)

\(=-1+\left(\dfrac{1}{3}-\dfrac{1}{3}\right)\)

\(=-1+0=-1\)

\(\dfrac{-13}{15}\) + \(\dfrac{5}{21}\) - \(\dfrac{1}{3}\) - \(\dfrac{2}{15}\) + \(\dfrac{2}{21}\)

=\(\dfrac{-13}{15}\) + \(\dfrac{2}{15}\) - \(\dfrac{5}{21}\) + \(\dfrac{2}{21}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-15}{15}\) + \(\dfrac{7}{21}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-3}{3}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-2}{3}\) - \(\dfrac{1}{3}\)

= \(\dfrac{-3}{3}\)

= -1