Question

Tính hợp lý: 

a) 45 . ( 5\(\frac{4}{15}-4\frac{7}{9}-1\frac{8}{45}\))

b) (\(\frac{7}{12}-\frac{1}{7}+\frac{5}{12}+\frac{6}{7}\)) : \(\frac{-5}{3}\)

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Answer 1

\(45\times\left(5\frac{4}{15}-4\frac{7}{9}-1\frac{8}{45}\right)\)

\(=45\times\left(\frac{79}{15}-\frac{43}{9}-\frac{53}{45}\right)\)

\(=45\times\left(\frac{237}{45}-\frac{215}{45}-\frac{53}{45}\right)\)

\(=45\times-\frac{31}{45}\)

\(=-31\)

Answer 2

\(b.\left(\frac{7}{12}-\frac{1}{7}+\frac{5}{12}+\frac{6}{7}\right)\div\frac{-5}{3}\)

\(=\left(\frac{7}{12}+\frac{5}{12}-\frac{1}{7}+\frac{6}{7}\right)\div\frac{-5}{3}\)

\(=\left(\frac{12}{12}-\frac{7}{7}\right)\div\frac{-5}{3}\)

\(=\left(1-1\right)\div\frac{-5}{3}\)

\(=0\div\frac{-5}{3}\)

\(=0\)