\(8-\dfrac{4}{5}=\dfrac{5}{x^2}\)

\(\dfrac{5}{36}=\dfrac{5}{6^2}=\dfrac{5}{x^2}\)

Vậy 6 = x 

1b            2b            3c              4d              5d          6c

Phân số ứng với 20 trang là \(1-\dfrac{1}{2}-\dfrac{2}{5}=\dfrac{1}{10}\) ( cuốn sách )

Số trang của cuốn sách là \(20:\dfrac{1}{10}=200\) ( trang )

Cách 1 : \(\dfrac{5}{7}\times\dfrac{3}{21}+\dfrac{2}{7}\times\dfrac{3}{21}=\dfrac{5}{49}+\dfrac{2}{49}=\dfrac{1}{7}\)

Cách 2 : \(\dfrac{5}{7}\times\dfrac{3}{21}+\dfrac{2}{7}\times\dfrac{3}{21}=\dfrac{3}{21}\times\left(\dfrac{5}{7}+\dfrac{2}{7}\right)=\dfrac{1}{7}\times1=\dfrac{1}{7}\)

\(\dfrac{4}{14}\times7+\dfrac{2}{9}\times3=\dfrac{4\times7}{2\times7}+\dfrac{2\times3}{3\times3}=2+\dfrac{2}{3}=\dfrac{8}{3}\)

What was matter with you yesterday ?

I had a headache so I didn't go to school yesterday

My friend hass a fever and she doesn't go to school

She should go to the doctor

He got covid-19 last month

He takes axercise every day

You shouldn't eat unhealthy food

Minh has beautiful white teeth

We should play sports regularly

A. days

\(\dfrac{-5}{18}+\dfrac{7}{12}-\dfrac{8}{9}=\dfrac{-10}{36}+\dfrac{21}{36}-\dfrac{32}{36}=\dfrac{-7}{12}\)

\(\dfrac{-5}{6}+\dfrac{3}{8}-\dfrac{7}{12}=\dfrac{-20}{24}+\dfrac{9}{24}-\dfrac{14}{24}=\dfrac{-25}{24}\)

\(1-\left(\dfrac{1}{3}+\dfrac{1}{2}\right)=1-\dfrac{5}{6}=\dfrac{1}{6}\)

familly: gia đình

fish: cá

rice: cơm

egg: trứng

bread: bánh mì