Question

tính:

Answer 1

a)\(=\dfrac{2}{5\times4}-\dfrac{5}{20}=\dfrac{2}{20}-\dfrac{5}{20}=-\dfrac{3}{20}\)

d)\(=\dfrac{5\times5\times4}{3\times4\times5}=\dfrac{5}{3}\)

Answer 2

`2/5 : 4 - 5/20 = 1/10 - 5/20 = -3/20`

`25/12 xx 4/5 = 5/3`

Answer 3

\(\dfrac{2}{5}\times\dfrac{1}{4}-\dfrac{1}{4}=\dfrac{1}{10}-\dfrac{1}{4}=\dfrac{2}{20}-\dfrac{5}{20}=\dfrac{-3}{20}\)

 

\(\dfrac{25\times4}{12\times5}=\dfrac{100}{60}=\dfrac{5}{3}\)